Okay another post from Robert of the Polish National Team:

He said that PG PPS sieve was 44% faster with his new 680 vs 570 BUT look at this on DirT


DirT (N680 | N570):
mysqlsha1 3:28 2:30
md5-1 ~30 min 25:48
md5-2 ~30 min ~22 min

No good...
Unless they come out with a driver release that cuts loose the 64 bit and floating point math then this card isn't very good for crunching!