It seems that edisoncarter's method of brute forcing button combinations to discover new San Andreas cheat codes has found a lot of publicity. News about him has even reached the distant realms of Slashdot and Joystiq.
So far the uncovered cheat codes have included infinite oxygen, gangs control the streets, reduced traffic, fast cars appear regularly and many more. Still to be found are the codes for all cars have nitrous, hydraulics, infinite health, armor and much much more. Edison himself has said this about his little 'project':
It's not an inside source or anything like that. I found them by scanning codes at high speed. I wired up a game pad to a PC's parallel port using optocouplers.
It was great to find an excuse to do a hardware project for a change. I haven't done wire-wrap since I was a kid. I'm certainly not recommending anyone try this. It takes some serious software to make this work.
For more information on these findings go see the cheats topic started by edisoncarter himself.