The 7970 is clock for clock the same as a GTX 680 and uses slight more power given its a bigger / more complex chip. AMD should of clocked the 7970/50s higher out the gate, the gap is much more minimal when overclocking comes into play.
This to me is nVidia hype, great marketing machine really, it's a revolution compared to their GTX 580 but not against the general trend in the industry. As someone else said, would be interesting to see if record bonuses are awarded to back this up.