I've been working on a web site framework called Pyplate for over a year now. It's finally ready for beta testing. You can download it here: http://www.pyplate.com/install-pyplate
Pyplate has been tested on Raspbian with Apache. Other web servers will be supported in the near future.
My CMS is much smaller and simpler than Wordpress, so it's ideal for running on a Pi. I use it to power my Raspberry Pi cluster. Pyplate also works on PCs and other devices - anything that can run Linux and Apache. It uses SQLite, and has built in page caching.
Check it out, and let me know how you get on with it.