Haven't tried them yet, but yeah, I bet that those Far Cry 2 numbers aren't entirely accurate in the real world. There could be strings attached, like 'at 640x480 with all details turned down' or at some ridiculous resolution with every whiz bang effect applied--ie. 7fps instead of 5fps on the highest end hardware.
I have seen significant improvements in newer games though, when it is a driver specifically optimized for it, so it may well be true for FC2. Even if it were only half that, it's still pretty impressive. I wonder how much of this was already there in the FC2 specific beta. I think I did get something near 30% compared with my original older set, and on the minimum framerate too, where it counts the most.
Those numbers for other games are probably the same ones they've been going on about for a while now.
Back when the first Detonator drivers came out, if I recall correctly, they were making similar claims and continued to do so for a long time afterward though it only applied relative to the pre-detonator drivers.
I'm happy to have some new WHQL drivers all the same because I've been using the FC2 betas. Though I've had no problems, I prefer a stable release.