After booting my machine, it's able to suspend correclty the first time, with the power button flashing slowly. I'm able to hit the button and have it come back on. The second time however, seems to never get all the way to sleep, I'll just come in to find a blank screen with the power button showing a steady light, and I have to do a hard reboot to get it back.
Running Xubuntu 12.04, 3.2.0-25-generic kernel, P67A-G43 motherboard with 2600K processor.