In the process of looking for a web based groupware, we came across Worldpilot.
The idea of Worldpilot is great. The layout in general is wonderful, and most of the front end ideas are well thought out.
But the backend. Oh the horrors. 2 users was enough to bog down a dual processor P3 550, and all I seemed to do was write patches to stop all the annoying zope errors.
I've so far spent around 20 hours fixing parts of it, and it's almost at the point where I'm tempted to throw it all away, and mimic the interface via perl and a proper database backend.
If you're looking for something neat in Zope/Python to hack, this is it. Otherwise, look elsewhere and wait for the next release.