Owners of most Core 2 Duo-based Macs already have machines with native 802.11n wireless support. You just can't use it right now. If you want to unlock it without dropping $180 on the new 802.11n AirPort Extreme that launches in February, however, you'll need to pay five bucks to download the AirPort Extreme 802.11n Enabler 1.0 patch which looks to come out at the same time. Apparently, some sort of legal mumbo-jumbo about unadvertised features is "forcing" Apple to take your lunch money. Couldn't they just have slapped a sticker on the box in a surreptitious place in a very tiny font?
Apple to impose 802.11n unlocking fee on Intel Mac owners [AppleInsider]