I came across some diagrams / photos of the USB 3.0 connector that was revealed in non-working prototype form at CES. It maintains backward compatibility with USB 2.0/1.1 by keeping the standard pins and adding 3.0 specific pins towards the front.
It seems odd that more pins would be required, given the 2.0 revision being able to use the existing layout. This probably indicates the USB controllers chips for USB 3.0 will not be compatible with the earlier 2.0 and 1.1 varieties. The USB 3.0 specification will not be finalised for a few more months. It almost feels as though CES jumped the gun by showing these pictures, it could be that a USB 3.0/2.0/1.1 driver chip will be designed in that time rendering the extra pins obselete. More details and photos over at reghardware.