Python is not such a bad language
That said, I have two small side projects (consultingwith.me and consultingwith.us) that I wanted to host on AppEngine. I have a fair amount of experience with the Java AppEngine SDK but my gut instinct was to go with the Python SDK using the default webapp library. After spending about 5 hours writing code, I find that Python is fairly comfortable. 7/9/2011 edit: I enjoyed getting a basic system working with Python (a great learning experience) but ended up writing a feature complete version in Rails and using that for several months. In the last week or so I have re-implemented it in Java + GWT for the Appengine.