You know? When Amazon started its' elastic hosting services (EC2, S3 and SimpleDB), the world of web development have changed.

AND NOW, GOOGLE WANT TO CHANGE IT MORE DRAMATICALLY!

Google App Engine, is a full stack of web application development environment based on Google Infrastructure, so basically you're deploying your application as reliable as google's one.

In contrast with Amazon's approach of allow users to upload a virtual machine to run in Amazon's cluster, Google want you to put only the application to their cluster. Currently it only support Python (but since I really love Python so I've no complain with that), and run in CGI mode. From it docs it is WSGI compliant too so basically I can use my favorite Pylons Web Framework there :-)

You can't write file in the App Engine environment just like in Amazon EC2, all data must be saved into DataStore.

It is now in Preview Release, with 10000 slots only.... well I'm too late -_-, but it is really really exciting to know that and I will probably deploy one or two of my apps there in future :-)

UPDATE: I've got a account at Google App Engine now