I came across this a couple of nights ago, and my housemate and I were playing with it last night. Basically, some clever chap has managed to make your PC emulate a PS3 controller through bluetooth, allowing you to re-bind all of the gamepad controls to whatever peripherals you've got on your PC, including your keyboard and mouse. Here's a video of the creator using it for CoD:
It's only supported in Linux at the moment, so if you don't have it already, grab Ubuntu and install it to a USB drive or use its fancy Windows installer which doesn't require and drive partitioning. I've also read that it's a pain to set up with non-Debian distros, so it's probably best to just stick with Ubuntu.
It's not perfect yet, and some games (like Killzone) are just set up bizarrely so they still feel a bit off with a mouse, but if you get it working, it's going to shit all over a gamepad, as you can see in the video.