I don't know too much, but I do know that the quality of the finish is awesome. I also know they heat the surface up to about 200 degrees C during the process.. Some say it can weaken your brakes/wheels - others swear it doesn't....
I'm going to get my brakes powder coated soon. I'm gonna pay slightly over the odds to have it done by Renault, because they'll fully remove and strip down the brakes.
Also, if anything goes wrong - they're to blame lol and they'll want me back in a few years to buy another Renault, no doubt.
Bearing in mind that on track, the callipers can get well over 600°C, I wouldn't worry about 200°C.
That goes for the wheels too. Don't forget that they're bolted to the disks, so a lot of that temp is going straight onto the wheel. If there was any problem getting wheels that hot, we'd all be driving around on our hubs by now.