Here is the deal on updating/upgrading your CD MBP to an AirPort with 802.11n:
The Mac Pro AirPort upgrade kit is the same AirPort card that goes in the MBP, only the current version has the capability for 802.11n with the enabler that ships with the new AirPort Extreme base station.
The kit is roughly $49.00 if you can find one - PowerMax had them last week - I know because I bought one - however, Apple has figured out what's up and appears to be cutting off supplies or limiting their sale due to the requirement that they be installed by an Apple tech.
The kit is an "Airport Extreme Wireless Upgrade Kit for Mac Pro (MA688Z/B)". There is an "A" version that is no longer available, but it appears that the difference may be the inclusion of the 802.11n enabler software in the "B" kit. I got a "B" kit and it has the CD with the enabler, but I already have a new AirPort base station, so I have the enabler software anyway.
This upgrade kit has the proper card with two antenna jacks - the card in the C2D MBPs has three antennas, although I have been told it will work as well. The card is located just above the hard drive, and is pretty easy to R&R from the looks of service manuals and online tutorials for replacement.
It's an easy and cheap upgrade if you can get an AirPort card. I've been told that a Dell 1500 wireless card will work as well, but I haven't seen the results from anyone trying this. The Dell cards are on eBay for less than a new AirPort card, but that's because many of them are take-outs, from what I've seen.
As mentioned in an earlier post in this thread, I am about to do this swap along with a hard drive swap as well. I'm hoping to do it this afternoon, time permitting, so I'll report back when I have finished.
MD