This happens on stock Karmic Beta as well.  Any USB drive plugged in after booting will not automount.  Mounting manually works as usual.

as can be seen below, the devices are recognized, but automounting fails due to an I/O error.


before plugging in devices, after restarting:
$ lsusb
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 005: ID 0bc2:3001 Seagate RSS LLC 
Bus 001 Device 004: ID 0b38:0010  
Bus 001 Device 003: ID 046d:c521 Logitech, Inc. MX620 Laser Cordless Mouse
Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

after plugging in two devices:
$ lsusb
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 011: ID 0781:5530 SanDisk Corp. 
Bus 001 Device 010: ID 0fca:8004 Research In Motion, Ltd. 
Bus 001 Device 005: ID 0bc2:3001 Seagate RSS LLC 
Bus 001 Device 004: ID 0b38:0010  
Bus 001 Device 003: ID 046d:c521 Logitech, Inc. MX620 Laser Cordless Mouse
Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

$ dmesg | tail -120
[ 3237.672088] usb 1-7: new high speed USB device using ehci_hcd and address 10
[ 3237.817510] usb 1-7: configuration #1 chosen from 1 choice
[ 3237.824268] scsi7 : SCSI emulation for USB Mass Storage devices
[ 3237.824505] usb-storage: device found at 10
[ 3237.824509] usb-storage: waiting for device to settle before scanning
[ 3238.368109] usb 1-8: new high speed USB device using ehci_hcd and address 11
[ 3238.505256] usb 1-8: configuration #1 chosen from 1 choice
[ 3238.505575] scsi8 : SCSI emulation for USB Mass Storage devices
[ 3238.505797] usb-storage: device found at 11
[ 3238.505801] usb-storage: waiting for device to settle before scanning
[ 3242.821017] usb-storage: device scan complete
[ 3242.822116] scsi 7:0:0:0: Direct-Access     RIM      BlackBerry SD    0003 PQ: 0 ANSI: 4 CCS
[ 3242.823146] sd 7:0:0:0: Attached scsi generic sg3 type 0
[ 3242.839590] sd 7:0:0:0: [sdc] Attached SCSI removable disk
[ 3243.504424] usb-storage: device scan complete
[ 3243.505006] scsi 8:0:0:0: Direct-Access     SanDisk  SanDisk Cruzer   8.02 PQ: 0 ANSI: 0 CCS
[ 3243.505845] scsi 8:0:0:1: CD-ROM            SanDisk  SanDisk Cruzer   8.02 PQ: 0 ANSI: 0
[ 3243.506857] sd 8:0:0:0: Attached scsi generic sg4 type 0
[ 3243.508047] sd 8:0:0:0: [sdd] 15695871 512-byte logical blocks: (8.03 GB/7.48 GiB)
[ 3243.509141] sd 8:0:0:0: [sdd] Write Protect is off
[ 3243.509147] sd 8:0:0:0: [sdd] Mode Sense: 45 00 00 08
[ 3243.509152] sd 8:0:0:0: [sdd] Assuming drive cache: write through
[ 3243.510520] sr1: scsi3-mmc drive: 48x/48x tray
[ 3243.510720] sr 8:0:0:1: Attached scsi CD-ROM sr1
[ 3243.510829] sr 8:0:0:1: Attached scsi generic sg5 type 5
[ 3243.516270] sd 8:0:0:0: [sdd] Assuming drive cache: write through
[ 3243.516279]  sdd: sdd1
[ 3243.523502] sd 8:0:0:0: [sdd] Assuming drive cache: write through
[ 3243.523507] sd 8:0:0:0: [sdd] Attached SCSI removable disk
[ 3243.661638] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.661646] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.661653] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.661663] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.661672] end_request: I/O error, dev sr1, sector 196352
[ 3243.661680] __ratelimit: 11 callbacks suppressed
[ 3243.661686] Buffer I/O error on device sr1, logical block 49088
[ 3243.661693] Buffer I/O error on device sr1, logical block 49089
[ 3243.669986] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.669995] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.670006] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.670018] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.670031] end_request: I/O error, dev sr1, sector 196352
[ 3243.670042] Buffer I/O error on device sr1, logical block 49088
[ 3243.670051] Buffer I/O error on device sr1, logical block 49089
[ 3243.675629] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.675635] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.675642] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.675651] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.675661] end_request: I/O error, dev sr1, sector 196584
[ 3243.675668] Buffer I/O error on device sr1, logical block 49146
[ 3243.675674] Buffer I/O error on device sr1, logical block 49147
[ 3243.680628] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.680634] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.680641] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.680649] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.680658] end_request: I/O error, dev sr1, sector 196584
[ 3243.680665] Buffer I/O error on device sr1, logical block 49146
[ 3243.680670] Buffer I/O error on device sr1, logical block 49147
[ 3243.689500] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.689507] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.689515] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.689523] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.689533] end_request: I/O error, dev sr1, sector 196600
[ 3243.689541] Buffer I/O error on device sr1, logical block 49150
[ 3243.708503] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.708510] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.708518] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.708527] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.708537] end_request: I/O error, dev sr1, sector 196600
[ 3243.708544] Buffer I/O error on device sr1, logical block 49150
[ 3243.715374] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.715379] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.715385] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.715393] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.715402] end_request: I/O error, dev sr1, sector 196600
[ 3243.721748] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.721753] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.721760] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.721768] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.721777] end_request: I/O error, dev sr1, sector 196600
[ 3243.730008] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.730015] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.730022] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.730031] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.730040] end_request: I/O error, dev sr1, sector 196600
[ 3243.737628] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.737635] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.737642] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.737651] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.737661] end_request: I/O error, dev sr1, sector 196600
[ 3243.742499] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.742505] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.742512] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.742520] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.742529] end_request: I/O error, dev sr1, sector 196600
[ 3243.747999] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.748029] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.748036] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.748044] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.748054] end_request: I/O error, dev sr1, sector 196536
[ 3243.754872] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.754878] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.754886] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.754894] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.754904] end_request: I/O error, dev sr1, sector 196592
[ 3243.759624] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.759630] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.759637] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.759645] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.759654] end_request: I/O error, dev sr1, sector 196600
[ 3243.764372] sr 8:0:0:1: [sr1] Unhandled sense code
[ 3243.764377] sr 8:0:0:1: [sr1] Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
[ 3243.764384] sr 8:0:0:1: [sr1] Sense Key : No Sense [current] 
[ 3243.764392] sr 8:0:0:1: [sr1] Add. Sense: No additional sense information
[ 3243.764401] end_request: I/O error, dev sr1, sector 196600
[ 3245.748505] sd 7:0:0:0: [sdc] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 3245.749991] sd 7:0:0:0: [sdc] Assuming drive cache: write through
[ 3245.753520] sd 7:0:0:0: [sdc] Assuming drive cache: write through
[ 3245.753533]  sdc: sdc1

$ mount -l
/dev/sda8 on / type ext3 (rw,relatime,errors=remount-ro)
proc on /proc type proc (rw)
none on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
udev on /dev type tmpfs (rw,mode=0755)
none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
none on /dev/shm type tmpfs (rw,nosuid,nodev)
none on /var/run type tmpfs (rw,nosuid,mode=0755)
none on /var/lock type tmpfs (rw,noexec,nosuid,nodev)
none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
/dev/sda7 on /boot type ext3 (rw,relatime)
/dev/sda2 on /c type fuseblk (rw,nosuid,nodev,allow_other,default_permissions,blksize=4096)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
gvfs-fuse-daemon on /home/mobusby/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=mobusby)