@ Xumbi
I am sure the circuit board of most (if not all) WiFi cards runs the whole length of the card. Even if the casing was taken off, you would still have a circuit board that is too long to fit in the internal Microdrive slot. Someone would have to basically desolder the chips from the board, design and build a shorter board, and solder to chips to it. Even if an individual was capable of the design part, most would not own or have access to the specialized equipment and resources needed to build that complex of a circiut board from scratch. I remember reading an article in PC Magazine about a company that offers such services, but the cost of building just a few boards would probably be prohibitively expensive.
My idea for the USB WiFi adapter would add bulk, but it would solve most user's complaint of having a WiFi card extending beyond the CF slot and making the unit difficult to hold.