App Engine requires you to code your app in a particular way to work on their platform, and that way will (to a large extent) only work on App Engine. This is

App Engine requires you to code your app in a particular way to work on their platform, and that way will (to a large extent) only work on App Engine. This is true, but it does make for a very nice deployment story; and Ian Bicking's silver lining (http://cloudsilverlining.org/ http://cloudsilverlining.org/) is (I think) a very interesting attempt to tell that story in a more generic way.