The Apple Magic Mouse drivers have been hacked to enable multi-touch support on Windows 7, according to

Thanks to a little hackery from Apple’s Bluetooth Update the Magic Mouses driver was extracted via WinRar resulting in a 32bit version and a 64bit version that you can install on any ordinary Windows PC that will enable all the scrolling ‘magic’ of the Magic Mouse.

You can download the 32-bit drivers here and the 64-bit drivers here