Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
What is the benefit of repairing disk permissions?
If any files installed by Apple have incorrect flags, they won't be incorrect any more. That's it. The corrections made by disk utility may or may not even matter, but people swear by this "remedy" for all manner of problems real and imagined, because it feels good to believe that something is being done.

On rare occasions, it can actually help matters, but far more often it's a coincidence or placebo effect, much like zapping the PRAM. But it's not going to hurt anything, so repair away :D
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.