Woot! Blizzard made the announcement yesterday - there's a gameplay video at the following link. It's about 20 minutes long and does a good job of showing off the new engine. Nothing about a release date yet - from what I can tell they're only just far enough along in their development to do the demo video. Still, I'm really excited.
I'm going to end up staying up until 10AM again when this comes up.
http://www.blizzard.com/diablo3/media/#movies