I'm using Heroku, which runs on Amazon. Since I'm not using Amazon service directly, this might actually be a more fair comparison (AWS by itself is lower level than Heroku and GAE). I don't plan to switch because I've been having a good experience with Heroku, I happen to know Rails and my project is already well underway.

What I would like to see is a functional language supported by a Heroku-type service or on GAE so that I could take the same in-cloud dev approach and learn a new language paradigm at the same time. I'm impulsive, so right now I'm interested in ErlyWeb. Python isn't different enough to warrant the jump, so unless I magically hit the level where I will benefit from Big Table (and I don't just use SimpleDB or Heroku doesn't pick up a doc-DB in the meantime), I'm fine where I am.

I am very glad they lifted the user limit, however, because I would like to see what the non-early-adopters start to produce.