I'm not quite sure about the steps prior to unmounting the device in respect to information you request. 'gvfs-mount -li' and 'udisks --dump' don't report a loop device after

1. mkdir /tmp/tmpmount
2. sudo mount -o loop ubuntu-10.04-desktop-i386.iso /tmp/tmpmount/
3. sudo umount /tmp/tmpmount

They do falsely report a loop device after a run of usb-creator though, while 'losetup -a' clearly indicated that there is none. This is the relevant part of 'udisks --dump' with usb-creator running:


========================================================================
Showing information for /org/freedesktop/UDisks/devices/loop0
  native-path:                 /sys/devices/virtual/block/loop0
  device:                      7:0
  device-file:                 /dev/loop0
    presentation:              /dev/loop0
  detected at:                 Di 14 Sep 2010 11:42:16 CEST
  system internal:             1
  removable:                   0
  has media:                   1 (detected at Di 14 Sep 2010 11:42:16 CEST)
    detects change:            0
    detection by polling:      0
    detection inhibitable:     0
    detection inhibited:       0
  is read only:                0
  is mounted:                  1
  mount paths:             /tmp/tmpLMNiRK
  mounted by uid:              0
  presentation hide:           0
  presentation nopolicy:       1
  presentation name:           
  presentation icon:           
  size:                        733419520
  block size:                  512
  job underway:                no
  usage:                       filesystem
  type:                        iso9660
  version:                     
  uuid:                        
  label:                       Ubuntu 10.04 LTS i386
  loop:
    filename:                  /home/ilja/ubuntu-10.04-desktop-i386.iso
  drive:
    vendor:                    Linux
    model:                     Loop: ubuntu-10.04-desktop-i386.iso
    revision:                  
    serial:                    
    WWN:                       
    detachable:                0
    can spindown:              0
    rotational media:          Yes, unknown rate
    write-cache:               unknown
    ejectable:                 0
    adapter:                   Unknown
    ports:
    similar devices:
    media:                     
      compat:                 
    interface:                 (unknown)
    if speed:                  (unknown)
    ATA SMART:                 not available

========================================================================


And this is after usb-creator finished its job and was closed:

========================================================================
Showing information for /org/freedesktop/UDisks/devices/loop0
  native-path:                 /sys/devices/virtual/block/loop0
  device:                      7:0
  device-file:                 /dev/loop0
    presentation:              /dev/loop0
  detected at:                 Di 14 Sep 2010 11:42:16 CEST
  system internal:             1
  removable:                   0
  has media:                   1 (detected at Di 14 Sep 2010 11:42:16 CEST)
    detects change:            0
    detection by polling:      0
    detection inhibitable:     0
    detection inhibited:       0
  is read only:                0
  is mounted:                  0
  mount paths:             
  mounted by uid:              0
  presentation hide:           0
  presentation nopolicy:       1
  presentation name:           
  presentation icon:           
  size:                        733419520
  block size:                  512
  job underway:                no
  usage:                       filesystem
  type:                        iso9660
  version:                     
  uuid:                        
  label:                       Ubuntu 10.04 LTS i386
  loop:
    filename:                  /home/ilja/ubuntu-10.04-desktop-i386.iso
  drive:
    vendor:                    Linux
    model:                     Loop: ubuntu-10.04-desktop-i386.iso
    revision:                  
    serial:                    
    WWN:                       
    detachable:                0
    can spindown:              0
    rotational media:          Yes, unknown rate
    write-cache:               unknown
    ejectable:                 0
    adapter:                   Unknown
    ports:
    similar devices:
    media:                     
      compat:                 
    interface:                 (unknown)
    if speed:                  (unknown)
    ATA SMART:                 not available

========================================================================



'gvfs-mount -li' reports:


Drive(2): 733 MB Datei
  Type: GProxyDrive (GProxyVolumeMonitorGdu)
  ids:
   unix-device: '/dev/loop0'
  themed icons:  [drive-removable-media-file]  [drive-removable-media]  [drive-removable]  [drive]
  is_media_removable=0
  has_media=1
  is_media_check_automatic=0
  can_poll_for_media=0
  can_eject=0
  can_start=0
  can_stop=0
  start_stop_type=unknown
  Volume(0): Ubuntu 10.04 LTS i386
    Type: GProxyVolume (GProxyVolumeMonitorGdu)
    ids:
     unix-device: '/dev/loop0'
     label: 'Ubuntu 10.04 LTS i386'
    themed icons:  [drive-removable-media-file]  [drive-removable-media]  [drive-removable]  [drive]
    can_mount=1
    can_eject=0
    should_automount=0


'losetup -a' shows that /dev/loop0 is not associated.

As there are two udev events after Step 2:

KERNEL[1284460875.988134] change   /devices/virtual/block/loop0 (block)
UDEV  [1284460876.002690] change   /devices/virtual/block/loop0 (block)

but none after Step 3, I assumed that these issues could be related. Please note that on Maverick 'losetup -d' is correctly reflected in the output of 'udevadm monitor', just not unmount of loop mounts.