It occurs to me that if they don't already use them in the new iMacs and MacBooks, sooner or later its likely that Apple will replace their onboard Broadcom-based Airport chipsets with Intel ones which in any other machine would carry a Centrino label.

My question is this then: Are there any PCMCIA cards which carry a Centrino label or use the same chipsets? And might such a card run under Airport software? And if so, would the necessary drivers get installed on any PowerPC Macs when updating?

I suppose Apple wouldn't bother compiling the code for PowerPC, even if that was all they had to do to make them work.