>That being said, I think this is a great idea. I don't love the Facebook OAuth flow and the amount of access most apps ask for.
You bring up a perfect point from a user's perspective and I agree with you. The challenge for Amazon is that there are two competing interests:
1. Users who don't want their entire life to be open to developers
2. Developers that want as much info as possible on the users
Facebook favors group #2 above, Amazon will probably favor group #1 above. If that ends up being the case, how many developers will be willing to utilize the OAuth service that doesn't give them as much info by default?