Yes, it's quite cool.
I couldn't see myself spending the money for a full-fledged Airport base station, but I'll get one of these when I feel the need to upgrade to a 802.11.g access point. (I'm presently using an older D-Link 802.11.b one, even though I've got a .g card. It's a leftover from my original iBook.) I like the idea of having the router be that small and completely out of the way. I don't know that I'd use the AirTunes stuff much, but it's a neat idea.
Tiny access point, wireless printer sharing and barely bigger than the power brick for my iBook? Sold!
(Yeah, wireless video would be nice too. Maybe they'll put that in the Airport Express Extreme.)