If you'd like to continue the conversation about App Engine, please check out the re-post of my article on Silicon Alley Insider (Peter edited it down and it's much more readable). Also, I wanted to point out this article by David Recordon, who pointed out the connection between App Engine and Facebook's Platform via Twitter from the unveiling event, and then posted about it around the same time my article was first posted here yesterday.
I think David is spot on, and I thank him for making me look less crazy.
Clearly, Google will be toe-ing the same line Facebook does when it comes to apps running on its platform. Think about it: if Facebook came out with its own "SuperWall" or "TopFriends" app, the developer community would be equally up in arms about, justly or not.
So, still today, I see App Engine as Facebook Platform 3 or 4.0, and not much to do with EC2.