
Demo Release Date - 14.02.12
Facebook users can receive early access to the demo for Xbox 360 only, and other Mass Effect 3 goodies by clicking here and following the instructions, and if you're lucky enough you'll receive a code to download the demo early.
Or you can watch part 1(and so on) of the demo here if you're not afraid of a few major spoilers.
So far I've received an avatar item, but must wait 2 hours before I can try again and you only receive 3 tries. To be honest, I'm not sure if I'll bother trying again with the demo being released in a matter of days, but for those who do wish to bother the offer's there.