A warning to anyone thinking of picking up the Atheros AR5BXB112 (which seems to be the only 802.11n option for laptops with a full-height slot and 3 antennas): some of the cards being sold on eBay have defective firmware and will not work properly in OS X (they will, however, work in Windows, making the case for a getting a replacement card to the seller difficult). They show up as "{none}" under Wi-Fi device in BIOS (D630n, A17) and gives the device ID "168c:abcd" in DPCIManager (should be 168c:0030), and are not recognized even when the device ID is edited into the relevant kext.
A quick Google search of the defective Device ID shows several threads with people encountering the same problem on both hackintosh and linux forums with this card. It seems to be an issue with the BIOS not properly initializing it. Also, from what I've read, I don't think it's possible to flash them with the correct EEPROM either, as the tools to do this don't appear to support the AR93xx chipset.
Just a heads-up!