After I replaced the front rotors a few weeks ago, I still had that annoying pulsation. That meant the back rotors were the culprit, not the front :(
So, I ordered up some rear rotors off ebay. They came in yesterday, and I installed them this morning. I took the Chevy Impala out for a ride, everything was fixed :)
Not too shabby, considering I did all four rotors and eight new pads for under $200 – try getting that kind of pricing from a dealership or a mechanic.