I found this thread while searching for answers to my own sqeak. Mine sounds like a cricket chirping but very fast...specifically whatever speed the engine is going. I've had my head under the hood a couple of times and pinned it down to the general area of the drive belts. One of said belts feels rubbery and generally good, the other feels hard and rough like sandpaper. I have to believe that it's the hardened belt, and there's probably a particularly bad patch somewhere on its length that causes the rhythm. It's that or bearings being tosted somewhere, but either way that belt is going away this weekend.