A friend of mine was attempting to filter Gmail using AI, is this similar to what you were thinking of? His product is: http://gtriage.com/
The numbers on good vs blab email are pretty typical, but for many folks even the "good" can be overwhelming. Our goal with Gtriage is finding the more important emails even within that smaller "good" set.
And new hotmail looks very cool. It's very nostalgic.. Mozilla's Raindrop project looked very promising as well.