Hello, I've got the same problem.
My usb camera had no problem to be mounted with gphoto2 in my Karmic.
When I installed the gnone-volume-manager (Version 2.24.1-3ubuntu1) is doens't mount anymore.
I tried to uninstall gnome-volume-manager, and reinstall udev, gphoto2, libgphoto... and still not working.
Let me give some system informations:
When I plug the camera i have:

>>>> tail -f /var/log/message:
kernel: [183586.411330] usb 2-3: new high speed USB device using ehci_hcd and address 10
kernel: [183586.594509] usb 2-3: configuration #1 chosen from 1 choice

>>>>> udevadm monitor:
KERNEL[1264625537.297637] add      /devices/pci0000:00/0000:00:04.1/usb2/2-3 (usb)
KERNEL[1264625537.297876] add      /devices/pci0000:00/0000:00:04.1/usb2/2-3/2-3:1.0 (usb)
UDEV  [1264625537.310658] add      /devices/pci0000:00/0000:00:04.1/usb2/2-3 (usb)
UDEV  [1264625537.317801] add      /devices/pci0000:00/0000:00:04.1/usb2/2-3/2-3:1.0 (usb)

>>>> udevadm test /devices/pci0000:00/0000:00:04.1/usb2/2-3
run_command: calling: test
udevadm_test: version 147
This program is for debugging only, it does not run any program,
specified by a RUN key. It may show incorrect results, because
some values may be different, or not available at a simulation run.

parse_file: reading '/etc/udev/rules.d/10-vboxdrv.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-gnupg.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-hplip.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-ia64.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-infiniband.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-isdn.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-libgphoto2-2.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-libibverbs1.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-libpisock9.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-libsane.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-pilot-links.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-ppc.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-usbmount.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-xserver-xorg-input-wacom.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-zaptel.rules' as rules file
parse_file: reading '/lib/udev/rules.d/45-fuse.rules' as rules file
parse_file: reading '/etc/udev/rules.d/45-libmtp7.rules' as rules file
parse_file: reading '/lib/udev/rules.d/45-libmtp8.rules' as rules file
parse_file: reading '/etc/udev/rules.d/45-libnjb5.rules' as rules file
parse_file: reading '/lib/udev/rules.d/50-firmware.rules' as rules file
parse_file: reading '/lib/udev/rules.d/50-udev-default.rules' as rules file
parse_file: reading '/lib/udev/rules.d/56-hpmud_support.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-cdrom_id.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-alsa.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-input.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-serial.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-storage-tape.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-storage.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-v4l.rules' as rules file
parse_file: reading '/lib/udev/rules.d/61-gnome-bluetooth-rfkill.rules' as rules file
parse_file: reading '/lib/udev/rules.d/61-mobile-action.rules' as rules file
parse_file: reading '/lib/udev/rules.d/61-option-modem-modeswitch.rules' as rules file
parse_file: reading '/lib/udev/rules.d/61-persistent-storage-edd.rules' as rules file
parse_file: reading '/lib/udev/rules.d/64-device-mapper.rules' as rules file
parse_file: reading '/lib/udev/rules.d/65-dmsetup.rules' as rules file
parse_file: reading '/lib/udev/rules.d/65-mdadm.vol_id.rules' as rules file
parse_file: reading '/lib/udev/rules.d/70-acl.rules' as rules file
parse_file: reading '/lib/udev/rules.d/70-hid2hci.rules' as rules file
parse_file: reading '/etc/udev/rules.d/70-persistent-cd.rules' as rules file
parse_file: reading '/etc/udev/rules.d/70-persistent-net.rules' as rules file
parse_file: reading '/lib/udev/rules.d/70-printers.rules' as rules file
parse_file: reading '/lib/udev/rules.d/75-cd-aliases-generator.rules' as rules file
parse_file: reading '/lib/udev/rules.d/75-net-description.rules' as rules file
parse_file: reading '/lib/udev/rules.d/75-persistent-net-generator.rules' as rules file
parse_file: reading '/lib/udev/rules.d/75-tty-description.rules' as rules file
parse_file: reading '/lib/udev/rules.d/77-mm-ericsson-mbm.rules' as rules file
parse_file: reading '/lib/udev/rules.d/77-mm-zte-port-types.rules' as rules file
parse_file: reading '/lib/udev/rules.d/78-sound-card.rules' as rules file
parse_file: reading '/lib/udev/rules.d/79-fstab_import.rules' as rules file
parse_file: reading '/lib/udev/rules.d/80-alsa.rules' as rules file
parse_file: reading '/lib/udev/rules.d/80-drivers.rules' as rules file
parse_file: reading '/lib/udev/rules.d/85-brltty.rules' as rules file
parse_file: reading '/lib/udev/rules.d/85-dmraid.rules' as rules file
parse_file: reading '/lib/udev/rules.d/85-hdparm.rules' as rules file
parse_file: reading '/lib/udev/rules.d/85-hplj10xx.rules' as rules file
parse_file: reading '/lib/udev/rules.d/85-lvm2.rules' as rules file
parse_file: reading '/lib/udev/rules.d/85-mdadm.rules' as rules file
parse_file: reading '/lib/udev/rules.d/85-pcmcia.rules' as rules file
parse_file: reading '/lib/udev/rules.d/85-regulatory.rules' as rules file
parse_file: reading '/lib/udev/rules.d/90-hal.rules' as rules file
parse_file: reading '/lib/udev/rules.d/90-pulseaudio.rules' as rules file
parse_file: reading '/lib/udev/rules.d/90-usb-media-players.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-devkit-disks.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-devkit-power-battery-recall-dell.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-devkit-power-battery-recall-fujitsu.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-devkit-power-battery-recall-gateway.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-devkit-power-battery-recall-ibm.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-devkit-power-battery-recall-lenovo.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-devkit-power-battery-recall-toshiba.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-devkit-power-csr.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-devkit-power-hid.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-devkit-power-wup.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-keymap.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-kpartx.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-udev-late.rules' as rules file
parse_file: reading '/lib/udev/rules.d/97-bluetooth.rules' as rules file
udev_rules_new: rules use 205692 bytes tokens (17141 * 12 bytes), 30565 bytes buffer
udev_rules_new: temporary index used 51100 bytes (2555 * 20 bytes)
udev_device_new_from_syspath: device 0x7f289c415990 has devpath '/devices/pci0000:00/0000:00:04.1/usb2/2-3'
udev_device_new_from_syspath: device 0x7f289c415c60 has devpath '/devices/pci0000:00/0000:00:04.1/usb2/2-3'
udev_device_read_db: device 0x7f289c415c60 filled with db file data
udev_rules_apply_to_event: GROUP 127 /etc/udev/rules.d/10-vboxdrv.rules:3
udev_rules_apply_to_event: MODE 0664 /etc/udev/rules.d/10-vboxdrv.rules:3
udev_device_new_from_syspath: device 0x7f289c4141b0 has devpath '/devices/pci0000:00/0000:00:04.1/usb2'
udev_device_new_from_syspath: device 0x7f289c414c30 has devpath '/devices/pci0000:00/0000:00:04.1'
udev_device_new_from_syspath: device 0x7f289c414ee0 has devpath '/devices/pci0000:00'
udev_rules_apply_to_event: IMPORT 'usb_id --export /devices/pci0000:00/0000:00:04.1/usb2/2-3' /lib/udev/rules.d/40-libgphoto2-2.rules:11
util_run_program: 'usb_id --export /devices/pci0000:00/0000:00:04.1/usb2/2-3' started
util_run_program: '/lib/udev/usb_id' (stdout) 'ID_VENDOR=Canon_Inc.'
util_run_program: '/lib/udev/usb_id' (stdout) 'ID_VENDOR_ENC=Canon\x20Inc.'
util_run_program: '/lib/udev/usb_id' (stdout) 'ID_VENDOR_ID=04a9'
util_run_program: '/lib/udev/usb_id' (stdout) 'ID_MODEL=Canon_Digital_Camera'
util_run_program: '/lib/udev/usb_id' (stdout) 'ID_MODEL_ENC=Canon\x20Digital\x20Camera'
util_run_program: '/lib/udev/usb_id' (stdout) 'ID_MODEL_ID=319b'
util_run_program: '/lib/udev/usb_id' (stdout) 'ID_REVISION=0002'
util_run_program: '/lib/udev/usb_id' (stdout) 'ID_SERIAL=Canon_Inc._Canon_Digital_Camera'
util_run_program: '/lib/udev/usb_id' (stdout) 'ID_BUS=usb'
util_run_program: '/lib/udev/usb_id' (stdout) 'ID_USB_INTERFACES=:060101:'
util_run_program: 'usb_id --export /devices/pci0000:00/0000:00:04.1/usb2/2-3' returned with exitcode 0
udev_rules_apply_to_event: GROUP 46 /lib/udev/rules.d/40-libgphoto2-2.rules:103
udev_rules_apply_to_event: MODE 0664 /lib/udev/rules.d/40-libgphoto2-2.rules:103
udev_rules_apply_to_event: GROUP 46 /lib/udev/rules.d/40-libgphoto2-2.rules:970
udev_rules_apply_to_event: MODE 0664 /lib/udev/rules.d/40-libgphoto2-2.rules:970
udev_rules_apply_to_event: LINK 'char/189:138' /lib/udev/rules.d/50-udev-default.rules:4
udev_rules_apply_to_event: MODE 0664 /lib/udev/rules.d/50-udev-default.rules:58
udev_rules_apply_to_event: RUN 'udev-acl --action=$env{ACTION} --device=$env{DEVNAME}' /lib/udev/rules.d/70-acl.rules:53
udev_rules_apply_to_event: RUN 'socket:@/org/freedesktop/hal/udev_event' /lib/udev/rules.d/90-hal.rules:2
udev_event_execute_rules: no node name set, will use kernel supplied name 'bus/usb/002/011'
udev_device_update_db: created db file for '/devices/pci0000:00/0000:00:04.1/usb2/2-3' in '/dev/.udev/db/usb:2-3'
udev_node_add: creating device node '/dev/bus/usb/002/011', devnum=189:138, mode=0664, uid=0, gid=46
udev_node_mknod: preserve file '/dev/bus/usb/002/011', because it has correct dev_t
node_symlink: preserve already existing symlink '/dev/char/189:138' to '../bus/usb/002/011'
udevadm_test: UDEV_LOG=6
udevadm_test: DEVPATH=/devices/pci0000:00/0000:00:04.1/usb2/2-3
udevadm_test: MAJOR=189
udevadm_test: MINOR=138
udevadm_test: DEVNAME=/dev/bus/usb/002/011
udevadm_test: DEVTYPE=usb_device
udevadm_test: DRIVER=usb
udevadm_test: PRODUCT=4a9/319b/2
udevadm_test: TYPE=0/0/0
udevadm_test: BUSNUM=002
udevadm_test: DEVNUM=011
udevadm_test: ACTION=add
udevadm_test: SUBSYSTEM=usb
udevadm_test: ID_VENDOR=Canon_Inc.
udevadm_test: ID_VENDOR_ENC=Canon\x20Inc.
udevadm_test: ID_VENDOR_ID=04a9
udevadm_test: ID_MODEL=Canon_Digital_Camera
udevadm_test: ID_MODEL_ENC=Canon\x20Digital\x20Camera
udevadm_test: ID_MODEL_ID=319b
udevadm_test: ID_REVISION=0002
udevadm_test: ID_SERIAL=Canon_Inc._Canon_Digital_Camera
udevadm_test: ID_BUS=usb
udevadm_test: ID_USB_INTERFACES=:060101:
udevadm_test: ID_GPHOTO2=1
udevadm_test: GPHOTO2_DRIVER=PTP
udevadm_test: DEVLINKS=/dev/char/189:138
udevadm_test: ACL_MANAGE=1
udevadm_test: run: 'udev-acl --action=add --device=/dev/bus/usb/002/011'
udevadm_test: run: 'socket:@/org/freedesktop/hal/udev_event'

And no device is mounted...
Please, what can I do?
Thanks