Howtoforge published a tutorial about enabling Compiz on Xubuntu 11.10

This tutorial shows how you can enable Compiz on a Xubuntu 11.10 (Oneiric Ocelot) desktop (the system must have a 3D-capable graphics card - I'm using an NVIDIA GeForce 8200 here). Xubuntu uses the Xfce desktop environment which is a fast and stable alternative for those that are not happy with Unity or Gnome 3. With Compiz you can use beautiful 3D effects like wobbly windows or a desktop cube on your desktop.

  Enabling Compiz On Xubuntu 11.10 (Oneiric Ocelot)