I'm pretty sure there has been talk of Skyrim being a steamworks game, so even if you can buy the game at midnight you won't be able to play it until it unlocks on steam. All the games on steam I've purchased didnt unlock right at midnight, like 10 edt for civ v I remember.
So don't plan on playing all night after 12 is all I'm saying.
FNV unlocked at 12:01 am PST
DA2 unlocked a few minutes late for me, around 12:08 PST
TW2 didn't unlock until around 7 or 8am this morning, unfortunately.
Hopefully Skyrim will follow in the vein of FNV, since Bethesda was the publisher