Created attachment 3534 
patch for xfdesktop-4.8.0 to correct icon tooltip bug.

When I plug in a usb stick it is automounted and I get a dialog appearing with a message saying "Volume mounted, the inserted volume was mounted automatically"
also a volume icon on the desktop.

A command line mount shows  
/dev/sda1 on / type ext3 (rw,barrier=1,commit=0)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=4,mode=620)
shm on /dev/shm type tmpfs (rw)
/dev/sda3 on /srv type ext3 (rw,commit=0)
/dev/sda2 on /home type ext3 (rw,commit=0)
usbfs on /proc/bus/usb type usbfs (rw,devgid=14,devmode=0660)
/dev/sdd1 on /media/b5511cc8-fcce-4143-b850-565f38479f09 type ext2 (rw,nosuid,nodev,uhelper=udisks)

Also Thunar shows the volume as open. 

However when I put the mouse over the icon I get a tooltip saying "Removable Volume Not mounted yet". Pressing the menu gives four selections: Open, Eject Volume, Properties, Applications. Selecting Open does nothing, selecting eject umounts the stick and the item disappears.

If the stick is installed when xfdesktop is started then the icon tooltip is "Removable Volume mounted ..." and Open brings up the Thunar.

I had a look at the code and it appears that the icon is created when the GVolumeManager sends a "volume-changed" signal, when this arrives the call g_volume_get_mount returns NULL this causes the icon tooltip to be set as shown.

I have added a patch to my xfdesktop which uses the "mount-added" and "mount-removed" GVolumeManager signals that as so far has corrected the problem for me.

My system is a LFS-6.6, BLFS system and xfce4.8.0 was compiled and installed by myself on Jan 23.
I have glib-2.27.9 with gudev included, gnome-disk-utility-2.32.0, gvfs-1.7.1 gtk+-2.20.1, udisks-1.0.0, libnotify-0.4.5, notification-daemon-0.4.0, and an unmodified linux-2.6.35.10 kernel.