Version: (using KDE 4.0.5)
Installed from: Ubuntu Packages
Taskmanager should have an option to only show minimized programs (like KDE3 can do). This will keep the taskbar from being all cluttered up if you have a lot of programs running. Se also bug #162568.
I've prepared a patch for this: http://reviewboard.vidsolbach.de/r/231/
Might get into KDE 4.2 if allowed to commit despite the soft freeze.