Search Tab turns up a few threads:
http://www.xoutpost.com/search.php?searchid=1545406
No one here, that I recall, uses them.
They look funky, but the main reason is reduced caliper/rotor ventilation, imo.
I'd pass on them.
Wheel Wax or any of the many waxes, "sealers" will help in reducing brake
dust build up and, afford easier cleaning.
GL,mD