WHICH DISK DID YOU START UP FROM?

If you're one of those people (and you know darn well who you are) who have multiple disks and multiple versions of the OS (like Tiger on one drive, Panther on another, Classic on another), in Tiger you can find out which disk you started up from by going under the Apple menu and choosing About This Mac. When you do this, you'll find a new info field has appeared, which shows you (in no uncertain terms) which disk you started up with.