$499 is the '09 price. Either you were looking at an '09 Rincon, or they upped the price because they had the '09s in stock and didn't want people to ask "Well, why would I spend...."
The thing is that '08 Rincon's are out of stock in Giant's warehouses except in weird sizes, and the '09s are available, and '09s haven't been officially released yet.
And the "Canyon" you mention is a YUKON. The Yukon is the same frame, but with a little bit nicer components, like a Dart3 fork, Tektro mech's, Deore shifting, etc.
Either way, you'll end up with a good bike; I've never had anyone complain about either. And the '09 frames are much better now than the previous years; it's basically the XTC frame.