Never have, never will. Consumers don't want a graphics chip in a console that costs £300, they want the entire console to cost £300.
That's not true.
The X1800XT was a high end card for PCs at the end of 2005 , it was only released around oct/nov around about the same time the 360 was released.
If the next generation xbox isn't releasing until 2013 then fingers crossed the 6670 is just temporary for game devs, otherwise it'll be way out of date before it releases.