I just got the Canon Rebel T1i, and the video is pretty good. Like Ryan said, audio sucks (compared to an actual video camera or boom mic) and there's no audio input, but for what it is it does the trick. It's far better then any mic on any point and click I've used.
Video looks pretty solid, and with the array of lenses you can get it gives you a lot of options for some really interesting shots. The Canons generally have less "wobble" when moving then the Nikons.
If your primary concern is video, it's best to go with a video camera. If you really want a good DSLR, but also want to be able to record HD video, then go with the DSLR cameras. My concern was the latter, and I'm quite happy with the T1i.