Currently pulseaudio keeps sound devices open during its entire lifetime, making
it impossible to use sound in the second session. For our fast user switching
effort, we've changed things so that devices now have acls that allow all users
with active sessions access, but that doesn't fix the problem with already
opened devices (and the kernel doesn't have revoke).
The short-term plan is to make pa react to ConsoleKit signals about the session
being deactivated, and voluntarily close devices then.
Monty is looking into this.
This is now fixed in Rawhide. PA now listens for HAL ACL changes and acts
appropriately. There still seem to be some bugs with HAL not setting ACLs always
properly. But that's a HAL bug (dn't know which bz number right now), not a PA
bug, so I am closing this one now.