I just run through the helloworld demo and confirm basically it works. I do not have a account on google appengine so I can not confirm the upload of app to the server.

The google appengine sdk is very easy to run on an iphone and the performance is not bad.

Are there any use of using google appengine in place of Django?

I am not sure how to run the dev web server on background, I just run it on a ssh session. May be someone can pack it as an application.