CherryPy is a hugely underappreciated project in the Python community.
Its HTTP implementation is top notch, its tool system is a great way to write custom modules, it has excellent WSGI support, and it's just about the fastest HTTP server in Python that takes a thread-based concurrency approach.
I was the first engineer hired on a team that built an online survey-research company. We started using twisted/nevow, but eventually moved to an in-house web framework on written on CherryPy. Lots of tools have come and gone (mostly, we've rewritten components we found lacking) but CherryPy has never let us down. We even ended up hiring a large portion of the CherryPy team.
Our experiences with it were positive enough that I'm building a startup right now on a similar CherryPy-based stack (at least partially--there's also a bit of Erlang involved for the high-concurrency stuff).
If you're considering stitching together your own Python Web framework--as many shops eventually do--I highly recommend CherryPy be used as the foundation.
Bad form replying to myself, but one more thing worth clarifying:
All the above being said, it's only fair to acknowledge that this isn't quite apples-to-apples when you look at CherryPy vs. something like Django. CherryPy isn't really a full-stack web framework, it's an HTTP server attached to a configuration and tool system that facilitates the creation of custom web frameworks.
