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.
First off, to the best of my knowledge, there are no PCMCIA cards which use the Intel wireless chipset. The Intel wireless chipsets for the Intel 915GM/915PM chipsets are available only as Mini-PCI cards. It has been a while, but I believe that PPC Macs use mini-PCI cards. So theoretically, while there are no drivers for them in MacOS X, an Intel Mini-PCI card could be put in a PPC Mac. There are Linux drivers that exist for Intel wireless cards, which may or may not compile in Linux for PPC. In any case this is moot. The new iMacs appear to use Mini-PCI Express cards from Broadcom and because they use a different bus they almost certainly use different drivers from the Mini-PCI cards. I am not certain that the new iMacs use a Mini-PCI Express card. The pictures I have seen of prototype Mini-PCI Express cards are narrower, longer, and have fewer contacts than a Mini-PCI card. As you may of may not already know, while the number of contacts and positions of the notches vary between a Mini-PCI card, an SGRAM SO-DIMM, an SDR RAM SO-DIMM, a DDR RAM SO-DIMM, and a DDR2 RAM SO-DIMM, the size of the connector is the same. The removable card with the Broadcom chip on it that I saw in the disassembly pictures of the new Intel iMacs looks narrower and longer than a standard SO-DIMM and more like a Micro SO-DIMM which means it is probably a Mini-PCI Express card. A Wireless Mini-PCI Express card regardless of brand would use a different driver and would need different firmware loaded onto it. These days, unless an expansion card needs to execute code to set itself up before the OS loads like in the case of a video card or a bootable device, the card would not have its own boot ROMs. Instead, the driver from the OS initializes the card and then makes its resources available to the OS. Most wireless cards these days do not have boot ROMs on them and instead have firmware loaded on to them by the driver. Besides, like most PC manufacturers now, Apple now probably has a code in the BIOS (or EFI if you want to call it that) to prevent the computer from booting into the OS if an unapproved wireless card is detected in the wireless card slot.
Also just to confuse things even more, while Apple generally releases the source code to as many drivers as they can, however there is no source code available for any wireless related hardware from Apple.