CODE MAY BE UNSTABLE AND LOCK YOUR X SERVER. In theory, it should kill and rerun itself after hanging for 20 seconds via alarm().
You should either install python-xlib via whatever means you are comfortable with, or you can run fetch-python-xlib.sh to fetch it from svn and then add the appropriate directory to your PYTHONPATH manually. Whimsy is developed against svn trunk so you could possibly have problems with older versions of python-xlib.
To run whimsy:
$ git clone git://github.com/mackstann/whimsy.git $ export PYTHONPATH=$PWD/whimsy:$PYTHONPATH $ python whimsy/whimsy/main.py
I generally run it in a loop in case it dies (which is very rare for me at this point) and I also launch it inside of screen:
export PYTHONPATH=$HOME/dev/whimsy screen -S whimsy -d -m -- sh -c 'while true; do python dev/whimsy/whimsy/main.py; done'
There are no window borders/decorations. There is support for viewports/large desktops (which are basically like virtual desktops, but are "physically" linked in that a window hanging off of one will show up partially in the next, instead of being completely isolated little worlds). There aren't many window management operations implemented other than the basics: moving, resizing, closing, raising, lowering, and executing commands. You can also execute arbitrary Python, of course.
Whimsy has been an on again, off again toy project of mine since sometime in 2005. I've been using it as my normal window manager since around March 2007.