That is a good question. I've done work on an '06 just recently and the rear wheels are the same, even the axle diameter is the same. I do have a question about the front wheel and axle though. The disc brake carrier is different, but I think the holes still line up.
If you find out for sure, please post it here. I want a set of the '06 front disc's for my '04, they look so open and clean. I really like the design of the new carrier, I do wish it was gold though...
Johnny