^Incorrect. Current games are written to be sequential and single threaded because that's what hardware was available. However, games can be EASILY multithreaded, since they are a compilation of so many different functions. For example:
You're running down a corridor somewhere in Black Mesa North (you know they're working on a third one already). While the first core is sending graphic information to the GPU and preloading textures that'll be appearing around the corner in a few moments, the second core is doing physics calculations and controlling enemy AI - possibly running sound as well. With traditional processors, this had to be all done at once and done right in sequence. With dual cores, tasks can be delegated out (much like SLI does) depending on workload and there is now enough processing power to start prefetching things, rather than loading them right when they're needed. Gaming has a LOT to gain from dual cores in the long run, they just have to be designed to take advantage of multithreading.