Scoble says Aero is not based on Avalon. I'm not so sure about that. To the best of my knowledge it is. I mean, it's entirely possible that it's not since it could skirt around Avalon and talk directly to DirectX and/or the Longhorn Display Driver Model (LDDM) itself, but then that would mean that I've been gettings some seriously mixed messages on the subject.
Can we get some third party clarification on this one? :)
Update:
As some others have pointed out, perhaps what Scoble meant is that Aero doesn't use the managed APIs of Avalon. It most likely just talks to the Media Integration Layer (MIL) API directly. While this isn't what most people think of as Avalon, it does fall under the technology's umbrella as far as I know. Click here for a great article that discusses what the MIL is all about, written by Mr. Avalon himself (Chris Anderson). Note that the article is a year old now and some of the terminology has changed, but the principals of the MIL covered in the article have not.