Dealer did it twice under warranty. I use Prestone dressing from Walmart whenever I get any type of squeak now. It holds up as well as a belt change (my warranty is gone). Mine only starts to sqeak after a long period of rain.
I have once under warranty...if you dont have warranty, go with dvs1's method of using a belt dressing, or your looking at about 400 bucks to have it replaced by the dealer