Currently Being ModeratedApr 21, 2012 4:51 PM (in response to vdufour)
Apple doesn't set one when shipping it from the factory; you'll be prompted to choose one the first time you turn the computer on. If you got it from someone, including Apple Support, ask them for it.
Currently Being ModeratedApr 22, 2012 2:32 AM (in response to vdufour)
It probably doesn't have one. Did you try to log in without inputting a password? Try the space bar too.