Former Ace's writer Johan DeGalas has recently put up a good article on how the much-discussed, industry-wide move to multicore CPUs will affect PC and console gaming. The best part of the article, and in fact of the series (the first article is available here) is Johan's interview with Tim Sweeney of Epic Games, who discusses in some detail the impact of multithreaded programming on game design and performance.
The gist of Sweeney's comments is that converting a game's serial codebase to thread-safe code that can be run on a multicore CPU is a very, very hard job. Nonetheless, it's a job that's growing increasingly necessary as both consoles and PCs are taking the multicore route. Tim forsees a fall in the number developers who roll their own game engines from scratch, because "implementing a multithreaded system requires two to three times the development and testing effort of implementing a comparable non-multithreaded system." This is going to make licensing a game engine that much more attractive in the future, since it keeps costs down and allows developers to focus on gameplay, art assets, etc.
Tim also discussed Unreal engine performance on multicore CPUs, stating that they expect to get a significant boost. Part of that boost will come from the fact that Direct3D and OS overhead, which accounts for as much as 50% of CPU cycles at times, will be moved to its own CPU. But Epic is also focused on selectively optimizing the parts of the engine that will benefit the most from multithreading.
If you're interested in learning more about multithreading in general, you might check out this article I did on the topic some time ago.
