My iTunes library lives on our laptop, but I’m often on our other “big” computer and want to listen to those tunes. I could stream between iTuneses, but I want this listening to count – i.e. increment play counts, let me change star ratings, etc. You can’t do that with iTunes streaming.
But now, with 2 computers, a wireless network, an iPhone running OS 2.0+, four cross-platform apps (3 of which are free), and a little scotch tape, my dream is possible.