Here is a hack just like my ADB to USB Mouse Conversion, only using the electronics from a newer Apple mouse. The creator, Alex Dawson, did a great job on the overhaul, especially with the positioning of the board and the placement of the optical sensor. It was recently posted on hackaday, which is where I learned of the hack.
On a related note, I just received my first issue of MAKE magazine, and I couldn’t be more thrilled with it. If you find the above hack even moderately interesting, you’ll want to get a subscription.