The wireless card on ebay was an 802.11b card with drivers. Since the 802.11b card is not a CardBuss card it is hardware compatible with the Amiga 1200/600 but you'd need a decent CPU to keep up with the 802.11b protocol and encryption.
I know there was someone working on drivers for such a card. It would involve modifying the drivers for PCMCIA networking cards but it wouldn't be impossible.
BTW, since 802.11G requires the bandwidth of CardBuss you won't see it on an Amiga 1200. I don't even know if the Amiga could handle that much bandwidth even if the card type weren't an issue.
