Now that the D&D Experience convention is happening, there's all sorts of new information about 4th edition coming out all over the place. Via The Velvet Dicebag, we have these notes from an attendee to the seminar given on the changes coming with 4th edition. Of Dice and Dragons has a link over to a pdf on the WotC pages entitled "What You Need to Know about D&D".
I'll post my thoughts on this later. So far, I'm not seeing anything too surprising, and I like some of what I'm hearing about D&D Insider. But nothing's blown my socks off yet.