I have been trying to diganose/fix this automount problem for quite a while.
Automount of CDs, DVDs and USB sticks works fine on two of my xubuntu 11.10 systems but not on my desktop system.
While trying to diagnose this I have found that it makes a difference using a remote display!
If I run thunar on my system called 'test' where it works I see:-
thunar-volman: Unsupported USB device type. thunar-volman: Unsupported USB device type. thunar-volman: Unknown block device type.
... and the USB stick automounts fine.
If I do exactly the same except by a remote ssh connection to 'test' from my desktop system 'chris', I see:-
thunar-volman: Unsupported USB device type. thunar-volman: Unsupported USB device type. thunar-volman: Unknown block device type. thunar-volman: Could not detect the volume corresponding to the device.
... and the USB stick *doesn't* automount.
When I run thunar locally on my desktop system I see the same output (and failure to mount) that I see when running via ssh on 'test'.
What on earth is going one?