The innovation in GAE is in the provision of an open SDK and how open sourced standards can provide portability. Whilst I understand the concerns being raised by pundits on various forms of PaaS (platform as a service), I think a significant point is being missed.
People seem to be so immersed in the detail of GAE, that they're missing the bigger picture, even though it's jumping up and down shouting "look at me, look at me!" with a sign saying "big picture" wrapped around its neck.
Either that or I've gone mad.