[pavlov]

Shameless plug -- I'm making a HTML5 animation tool called Radi that outputs to canvas for realtime rendering. It also supports the <video> tag, so you can seamlessly mix vector graphics and pre-rendered video.

It's available as a free beta (currently Mac-only): http://radiapp.com

[Stuk]

Looks very interesting, it would be great if you could put a video of the app in action on that page. I don't have a Mac so I can't try it out myself.