This is a bit of an "un-hint." There have been many hints here on using iTunes with Fast User Switching. In versions of iTunes before 4.5, you could only run one instance of iTunes on a given machine, so some hints involved stopping iTunes when switching accounts or from another account. Other hints involved sharing an iTunes library between accounts.
Apple quietly introduced support for Fast User Switching in iTunes 4.5. You can now have iTunes running in multiple accounts simultaneously. If the iTunes/Sharing preferences in each account are set to share music and to look for shared music, then the library of one account will be accessible within iTunes on the other account. A couple of caveats on sharing libraries:
- iTunes must be running in the account whose library is being shared, otherwise the other accounts cannot see the shared library.
- The sharing is just like that between multiple computers on the local network -- a user in one account cannot modify the library in another account except by following one of the old hints.
One other interesting feature of the Fast User Switching support is that the instances of iTunes running in different accounts keep playing even when you switch accounts. This means that you can have multiple songs playing simultaneously, one from each account. I'm not immediately sure why that would be useful, but it is nice that I can switch to my wife's account to do some system maintenance without having my music stop.