The Adapter in Question was made, because oringinally, the Airport was not going to be a PCMCIA card, but a proprietary card of similar size. Once the Cost Factor was figured, and the PCMCIA card were chosen. The problem was many Powerbooks and iMacs had already shipped with the new port. Apple Designed an adapter, and that is the one in question. Thankfully, the adapter comes with most new "old" Airport Cards. Infact I have one kicking around at home, I think. If you can't get one with the Airport Card, talk to a local Apple Authorized Reseller, they probabily have hundreds just lying around.
TEG