I haven't bred specifically for IVs (well, maybe a Hasty Flygon that was intended for Emerald Battle Frontier usage), but I have gone on an IV-comparing spree with certain Pokemon. I caught Abra en masse (to use their Synchronize ability in the future to sync the Natures of wild Pokemon to preferred ones) and Ditto (for breeding), paying particular care to the IVs (the IV man in the Battle Frontier is very convenient!).
I haven't attempted IV breeding in Generations 4 or 5 yet, but I'm likely going to pay even more attention to it, due to the RNG abuse potential and the new additional effects of the post-Generation 3 EV-enhancing items (basically, all the "Power" items/braces excluding the Macho Brace) that were introduced in HGSS. >_>