Be safe with your accounts duders. I think Blizzard is requiring authenticators for access to RMAH, but not sure about that yet.
But from what I can see they have not enabled commodity auctions in the RMAH yet (gems, recipies, etc), only items. So buyer beware! Prices are utterly insane as is expected in the opening days, when items don't have a good value defined yet. Do your homework and make sure you remember that there is a 30% cut taken from what you sell (15% Blizzard, 15% Paypal) when you choose to cash out. RMAH Transaction fee is $1, and minimum bid value is $1.25