Got to hand it to the MacBidouille/HardMac crew, they are not easily discouraged. Rather than accept the perpetual second-class status of the Core Duo MacBook 802.11g Airport Extreme card, they bravely attempted to transplant the N-capable wireless card from a Mac Pro into the forlorn laptop. The result? A fully functional battle station 802.11n laptop, with no apparent ill effects. Well done! (The article goes on to note that they saw full N speed from the card, and that the same surgery could be done on a MacBook Pro.)
Is this the sort of surgery you'll want to be performing for yourself? Well, even allowing that you can get your hands on the repair/replacement part for the Mac Pro, it's worth noting that the MacBook disassembly process involves 25 screws of varying lengths and sizes: not for the faint of screwdriver.