At the Dragon they were showing the Prima Wheel Sonax, it has a chemical reaction with the brake dust and allows you to wash it off easily. It changes color as it works. It goes on green and turns a dark red as it lifts the brake dust
Mark bought it and I think he liked it.
I'm using Armoral wheel protectant right now, but I think Prima might have one and if they do, I'll just switch to that.
I found it here and they have images at the bottom that explain how it works
http://www.detailersdomain.com/Sonax-Full-Effect-3-Pack-Kit_p_593.html