Matt Cutts of Google says no.  Cutts addressed this question in a Help video recently, which SearchEngineWatch.com posted.

“Does using stock photos on your page have a negative effect on your ranking? To the best of my knowledge the answer is no. Do original photos help help you? To the best of my knowledge it doesn’t really make a difference whether it’s a stock photo versus an original photo," Cutts said in the video.

But of course, in typical Cutts' fashion, he wondered out loud if having original photos would be an indication of quality.  He added that they may take a look at that in the future.  But for now…the use of stock photos does not impact your search ranking.