I've seen the video features of the D90 and 5d Mk II as sort of novelties, or maybe useful for photo journalists.
But clearly, there's some opportunity for people to create real art with it too. Check out Vincent LaForet's work in progress:
7 Days, 7 Shoots - EOS 5D MKII Vincent Laforet’s Blog
Seeing that kind of stuff makes me want to run out and buy one today, but then I realize that I still need
* talent
* models
* scenes
and a lot more.
Still, inspiring.
edit: while the video quality is impressive, what really amazed me is how he used it. Absolutely gorgeous shooting in every way, and that's what made me stop and think moreso than the merits of the camera.