Best Buy tests used video game sales on CNN Money describes a new program being tested in four Best Buy stores in Illinois and California, quoting an industry analyst as saying: "We think there is a reasonable chance that Best Buy will expand used video game product sales to most of its 700+ stores during the next two years." The article does not seem to distinguish between PC and console games, though Gamestop, the major competitor mentioned in this field, does not actually sell used PC games. The article discusses implications of such a program, like the possibility that this would spur higher prices due to increased tech support falling on publishers or accelerate the push toward more widespread digital distribution. They also hear from Epic's Mark Rein on the topic:

Mark Rein, vice president of Epic Games, creators of the "Unreal" franchise as well as the upcoming Xbox 360 game "Gears of War," has vociferously argued against retail sales of used games in the past. The expansion of a major retailer into the field, he said, is disheartening.

"We pay to be in Best Buy's flyers," he said. "We pay market development funds. Publishers drive gaming traffic to these stores. To have them resell the games, with developers having no participation, that's just wrong. That's just fleecing us."
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"Are they going to sell used copies of Microsoft Office -- and if not, why not?," asked Rein. "Why is that Microsoft (Research) has no objections to you reselling a copy of 'Halo,' but if you try it with Office, they'll come down on you like a ton on bricks?"