I am not looking around for the odd freak card that can achieve this. The norm for a gtx580 overclock and added performance is not gonna be anywhere near 40%. I dont see your problem they are not reviewing a gtx580. They showed oc performance on the card they are reviewing. The gains were nice and in no way were meant to make the gtx580 look bad.
but from a buyers point of view (i have been waiting for this card) a gtx 580 is probably a better buy or wait and see what nvdia brings again (i am however sick of waiting)
I only play bf3 so im waiting to be able to play on ultra settings