Those are just the ones I know for a fact because I've personally bothered to check via task manager; Supreme Commander, both Crysis games, Far Cry 2, FSX all scale well with 4 cores, just not as well as newer titles. [The three I gave had 85% scaling or more across 4 cores, the others tend to drop off a bit after the second core, but still use 4.]
Nevermind that Windows generally has several HUNDRED threads going at one time, so more cores will at least make certain commands more "snappy", even if it has no effect whatsoever on FPS once a program actually starts.
Right now, Quads are fine for 99.9% of all users. But its clear programmers are finally starting to thread well [IE: Scaling instead of having some pre-defined limit of cores used]. For serious gamers, Duo's are already dead.
Either way, 80% of the time, the GPU is the bigger bottleneck anyways...
Finally, I'd note the biggest bottleneck is the Windows Sheduler, which due to very deep down memory considerations, preferes to stick all programs on a single core. [I could go into a very long dissertation as to why, if you'd prefer]