Slashdot discussion on Windows 7's Virtual XP Mode and what sort of pain it could cause IT professionals. Personally I think it's a neat idea to allow a transition for users, as well as a nice bridge for people who are still on XP and not yet up to Vista who may begin to feel really left behind when 7 hits sometime (this year maybe?).

That said, I don't have to support windows machines myself, much less windows machines with 2 copies of windows running on every desktop!