This has been dicussed a while back but i just wanted to share a tip that i stumbled on.
I have my PB Alu 15" (128vram) hooked up to my apple 20" LCD most of the time. Sometimes I want to plug and unplug stuff when its asleep. (like when i want to unplug it from the LCD and use my pb in a different room.)
Here's my tip:
unplug you power cord.
then you can unplug all your devices and your PB will not wake from sleep.
I don't know if its because i have a LCD plugged into my DVI port.
Hope this helps.