USB 3.0 can already be found on a lot of computers in the notebook and desktop market today. All of these computers use a third party controller for the USB 3.0 ports though because neither Intel nor AMD offer native support for the USB 3.0 port in their chipsets. AMD has announced that it will be changing that.
AMD has announced that it will build support for USB 3.0 into its upcoming A75 and A70M Fusion chipsets. AMD's Phil Hughes told CNET in an email that the chipsets are shipping today. That should mean machines running the new chipsets will starting hitting the market before long bringing native USB 3.0. Intel will be the only major chipmaker that doesn't support USB 3.0 natively.
One of the reasons that support for USB 3.0 isn't more widespread today is that both AMD and Intel didn't offer support for the standard in their silicon from the start. Once this support is integrated, the ports will become much more common. The USB 3.0 port is backwards compatible with all older USB protocols and with chipset support, we will see all USB ports on notebooks and desktops move to USB 3.0 speed. Intel still maintains that it will support USB 3.0 in the future and that the ThunderBolt tech it is pushing with Apple right now will complement USB 3.0, not replace it.