Powdercoating is far from a new process. As actionman said, it is ionised particles that create a very strong finish. That being said, I have read that good spray painting will create the same sort of finish and is much cheaper (to powdercoat in Melbourne is a fair bit more than $100, plus you have to strip the existing surface). The other downside is that it is very difficult to get it off if you decide you want to change the colour of the wheels again.