On a whim I setup a Google App Engine account and an hour later I had the hello world Groovy example up and running. They recently added a Java option to the current Python stack. I pulled a quick tutorial from Guillaume Laforge on launching a Groovy web app. A few downloads and a bit of configuration and the app was deployed. Pretty impressive, especially for a free place to do Groovy deploys. The real fun will come when you can just dump Grails apps directly up there.