When I sent the original DMCA notices to Google, and referenced that my client's homepage was indexed in Google on a multitude of Appspot subdomains, they had absolutely no idea what I was talking about.
This is exactly what bothered me. Google, by the nature of what they do, should understand the situation *more* than anyone else. They don't. Leverage appspot proxies as part of a negative seo campaign is very common. They don't seem to know, or perhaps don't care.
My earlier rant about Google probably understanding it if it were something they cared about drives off that point. I didn't take the google home page as a good example because it doesn't even have a complete sentence on it. But, if, for example, the Adsense blog was being proxied, and the proxied copy started ranking for terms...I bet they would not only DMCA the content, they would shut down that particular appspot app and ban the owner.