Bulldozer is a complete architecture remake and is still under NDA. Any "claims" of performance are photoshops. Most modern games are utilizing 3 cores and have the 4th parked for Windows based threads. Some use 4 cores+ IE GTA4, Mafia 2, BFBC2, Crysis 2. With more and more games being console ports they are coded horribly on the pc and use lots of cpu power. If the trend continues i dont see why they wont start using 6-8 cores soon. Since the big bucks are in console games... porting with lazy programers and bad code=lots of cpu usage.
Tbf I have my doubts these same lazy programmers will even add the support for those 5+ cores.porting with lazy programers and bad code=lots of cpu usage.
Probably lazy is the wrong word.... From a business standpoint, its much more effictive to spend as little time recoding the same game as possible, demanding higher system specs for HD or close to HD games isn't an issue since gamers wanting to play those games will typically upgrade their PC rather than say "I'm not going to buy this game, becuase my PC can't handle it."
So very simply why spend 1000 man hours recoding a game to work with more threads when you spend 50 man hours recoding it to work with more cores.
(numbers are purely for illustrative purposes, and it is very unlikely they represent the actual amount of time spent)