Screaming Penguin - Source Does Matter

KDE simply put kicks arse. It gets better every rev and 3.1 looks like no exception. 3.1 sports Konqueror with tabbed browsing, a new "VNC compatible" desktop sharing feature (great for remote access and administration, etc), more "eye candy" in the way of icons and a bunch of other bug fixes and enhancements, etc.

Also note that KDE is releasing Kroupware in the near future and its supposed to be an entire groupware suite for KDE (not many details on where this project is, but it and several other similar ones are in the works.)

For more check the linked KDE 3.1 promo article and feature plan.   KDE 3.1 promo article