No card on the market currently explicitly mentions support of the 5ghz band (if you find one please prove me wrong and save me some time cause I am actually looking for one).
I think Apple is using some restricted top secret engineering samples with the C2D machines, that is why we needed to buy a 802.11n enabler to activate the additional parts of the firmware: it probably hasn't passed FCC approval back then yet!
The good news, apple uses the same chipset as them, so the apple might actually for them, or might need some minor tweeking to work with them. However, if I had a definite anwer I'd have two of them already.