I'm sharing my PC with my wife and my sister on regular basis. There are several issues when we switch from one user to another, such as the NetworkManager icon being present only on the first account (which is ridiculous).
A similar problem occurs when there is a DVD in the drive. When a second user logs in, the DVD cannot be seen (unmounted, ejected) until you physically eject the disk (i.e. press the button on the drive itself) and reinsert it.
My amateurish guess tells me that automount mounts the disk with the current user's permissions so the other can't unmount it. This is a bit absurd since every user has the "Mount user-space filesystems (FUSE)" and "Use CD-ROM drives" permissions (I am the only sudoer, though).
Is there any way this could be "fixed"? It's only a nuisance, but I can already see my co-users asking questions and being annoyed.. :)