I installed Ubuntu 11.10 on a brand new Lenovo Thinkpad W520, but no matter what I tried to do to enable wobbly windows, the setting wouldn't take effect.
I finally discovered (after running lspci | grep VGA) that I had two graphics adapters enabled.
The issue was that this model of ThinkPad has a BIOS setting called "Optimus" that will switch between the integrated graphics adapter and the nVIDIA graphics adapter, upon request of the operating system. However, as is noted in the BIOS setting screen, this feature must be supported by the operating system and is not recommended unless running Windows 7.
Switching the display BIOS setting to "Discrete" forces the laptop to always use the nVIDIA graphics adapter, and after saving this setting wobbly windows and other compiz effects became enabled.