New standards like these take a long time to implement, you need new drivers, cables, ports and the hardware to utilize them. That's a lot of different manufacturers and companies.
From what I've read however we should start seeing more consumer USB 3.0 products in 2010, which will of course include motherboards. I expect it will only be high end boards that adopt them first, but over 2010 I expect it will filter down to more mainstream boards as more products are released that support them. There is of course no point for the motherboard manufacturers to have paid for the USB 3.0 controllers etc on mainstream boards if there are no peripherals released that supports the new speeds.