i got leather... i just wipe the seats down with some mcguiar leather wipes about once a month. since its winter time there's no real worry about the sun fading the or cracking the leather.. and i'll be getting tints too so that'll help once the summer rolls around.
but yea.. only maintenance i've heard of is wipes to keep it soft and supple and try not to park under direct sunlight
Try to keep the seats out of direct sunlight -- a good excuse for getting your side windows tinted if it's legal in your state. You can also buy "leather conditioner" and use that -- I know that Meguiar's makes some. Do NOT use Armor All on them.