I created two test users with the live cd image. Logged in as the livecd user, I selected the user name menu in the top right corner and pressed "switch user". In the new gdm prompt, I logged in as the first test user.

When logged in as test user 1, I then selected "Quit"/"Log out" and pressed the "Switch user" button in the windows that appeared. In the gdm prompt, I clicked the live cd user that told me it was logged in. It switched to the correct x display, but then froze and crashed, leaving me at a new gdm prompted telling me that only the first test user was logged in (no longer the live cd user).

I pressed the test user 1 entry in the gdm list, then entered the password, and it switched to the correct x display again. Again it froze, this time just hanging, and only a hard reset would bring it back. (not "back", but .. you know).