Google App Engine or Django?
If you plan to use Django on app engine, then chances are you will want to use Djangos ORM. Which means.. you will probably be looking at Django non-rel. However there are a few things to consider:

Django non-rel runs a few versions behind the latest django release, so some modern features (such as advanced timezone support) are not supported, as of the moment, you will just have to wait.
Django non-rel does not support some features such as Django's transactions API and none of the native app engine transaction modules work ether.

so all in all, fine for a small simple projects, but when things get more complicated, django non-rel falls short.
I've been learning Python and now I'd like to learn a Python-based web framework.  I'm considering Google App Engine and Django.  Which one should I choose?  What are their unique features and learning curves?