Last week Jordi Fernández gave me a quick hands-on tutorial for a working Beryl setup on Debian. He owns a Dell Latitude D620 running Debian GNU/Linux just like mine, so leeching his setup was even easier for me.
Read it at this blog
I have the official nvidia drivers (1.0-8776) installed via module-assistant and a Beryl version that is kind of old (0.2.0+svn20070205-r3687+imudebian0, rather ancient in Internet Time). This worked immediately for me but Your Mileage May Vary.
There you have it. A working beryl setup in a few minutes. Thanks to Jordi for this tutorial and the rather impressive demo that followed, and to the Compiz and Beryl developers for their hard work.