Hi and thanks for this nice tool!
I just started using PyTyle with Metacity 2.30.2 on Ubuntu 10.10.
It is working fine, the only thing I changed was the window ignore list, where I added 'desktop_window', which is Metacity's desktop window class.
Maybe you can do this for the default configuration, making it easier to use for new users.
Then I think you can add Metacity to the list of working WMs.
Keep up the good work!