Comment 5 for bug 378668

Who-hooo, I've just discovered that compiz is actually installed!
  Installed: (none)
  Candidate: 1:0.8.2-0ubuntu8
  Version table:
     1:0.8.2-0ubuntu8 0
        500 jaunty/main Packages

I always thought that was only for silly rotating screen effects and the like... eating your memory and cpu for nothing... never expected it to be in a Xubuntu.
How do I find out if it's active in some way or another? I only find Settings > Window Manager Tweaks > Compositor: Everything disabled