Did anybody try to get play 2.0 on GAE? Play is now based on sbt, technically sbt-appengine-plugin should work. And if you have tried, what is your datastore setup?
I don't beleive it will work as, if I'm not mistaken, GAE requires a war file, which Play 2.0 can't generate.
That will not be possible until Play 2.1 (as per current plan)
You might want to try Ninja Web Framework and the Ninja Appengine module. One of the main reasons why we started Ninja was App Engine support.