i would definitely pick an orc since they are the best warrior class in the game, and have been for awhile.
free ap trinket on a 2 minute cd to give arms something extra since you dont have any cd's to use during burn phases other than shattering throw. cataclysm wont be out for awhile so you dont have to worry really about the "no more ap" thing.
you get 5 expertise with axes, which makes it very easy to hit fury expertise cap (axes are the best dps weapons in the game as well, excluding ulduar). plus the legendary dps axe that will drop in icecrown will make orcs even more attractive. yeh people talk about how there are only 2 options in game for tank axes, but last laugh compared to titanguard is basically the same stats. watch, i'd almost bet money the next tanking weapon released in the next raid zone will be an axe. (how long did orcs wait to use their axe racial in bc....black temple)
minor stun resist is meh since you wont get stunned much as dps or tank, but helps in arenas quite a bit.
as tanking, there isnt much, but the other horde classes dont have any tanking related racials except tauren, and even then theirs is minor (5% base hp bonus). plus you get a little threat boost with blood fury since aoe is based off ap (tclap and shockwave).
if you do anything other than just tank, orcs will win hands down. if all you are going to do is tank, its a tie between orcs and taurens (only because of cows ~500 hp difference from 5% base hp).
im actually waiting on race changes to become available so i can switch my tauren to orc.
edit: forgot to mention the best orc racial, pro looking shoulders!