With a few exceptions in the newer releases, by and large games still are not coded to take advantage of a large number of independent threads. Therefore core count is not a very high priority when it comes to gaming. It helps, sure, if for no other reason than your game can run on one or two cores while the rest of the apps and services which are running at the time may use cycles on the unloaded ones. But IMHO, (at the moment) the Quads which are just now coming intp common use are more than adequate for current and next gen titles. I should think that the added cost of a (server chip, BTW) "6 Core Plus Hyperthreading" monster would deliver very little in real life usage on the desktop in a gaming situation. One would need to do heavy encoding and rendering to tax the thing.
Sure - that will change over time (years?), but understand that massively paralell code is *very* hard to write - which means additional up front costs the publishers don't want to pay. And keep in mind most computers are still singles and duals (though this is changing), so were publishers to write to take full advantage of a massively paralell system, then it's a good bet their games would suffer on the majority of their player base's systems. Not to mention the big bottleneck now is still Video.
(...and yes, I fully realize this is a repeat of many of the same arguments in the "Dual versus Quad" wars of a couple years ago. I understand that we will "get there" and enjoy the benefits of massively paralell systems. Publishers *will* take advantage sooner or later. But IMHO, We 'ain't there quite yet...)