I too have the same problem. I have a Macbook 13" A1280 and the airport card just quit out of the blue. It says "Airport card not detected" and it won't allow me to turn airport card on. If I reboot it about a dozen times it will suddenly be working again, but will inevitably crash they system. The only thing I can do at this point is reboot and hope the airport card will be detected after reboot, but it's a 50/50 chance. Most often it is not detected.
After reading the forum posts here I think I'll just bring it to the Apple store and see what they come up with. I'll post what they say here.