DICE has their own, very powerful gaming engine - Frostbite. The engine was used in Battlefield: Bad Company...but not in BF Heroes or DICE's Mirror's Edge game. What exactly is the firm doing with this game engine?
Way back in late June, DICE said they were working on 5 Battlefield games. Two are known - Battlefield Bad Company and Battlefield Heroes. One used Frostbite, the other uses the BF2142 engine. Of the other three games little is known other than one will be a console-exclusive game and the other a Korean-market only game. Chances are the console game uses Frostbite but not the Korean game.
Will the fifth unmentioned game use Frostbite? Is that why we haven't seen it used elsewhere, the resources are being used to develop something special? Maybe it's...BF3?
Join in on this loose collection of thought and see if the marginal logic makes any sense.