Gordon's Tech: Multiuser machines and devices: the next most messed up part of OS X: "The real problem shows up with iPods however, and presumably with an iPhone as well.Well, iTunes 7.6 now has an option to TURN OFF iPhone and iPod sync. I set that option for every user on the multi-user iMac.
Each user account tries to seize control of the iPod. So if I sync on my account, then switch to my wife's account, the iPod can go into a limbo state. It thinks it's attached, but the OS says it isn't."
Big problem made smaller.
BTW, they also fixed the $$%!$ broken smart playlist functionality.