Thanks for your input! I've been dabbling a bit with node.js already on small projects, and I like what I see so far. I was hoping to use GAE though, but I guess that is not really a requirement. I do however worry that my relative inexperience with node.js would make it harder (for me) to really integrate everything I need like authentication etc. Of course, I might be wrong!

In pure development speed I think doing it in Django would be the fastest for me, but I hate using the "wrong" tool for the job.