Gamesindustry.biz reports that Epic's mega-hit Gears of War has sold 3 million copies worldwide:

Microsoft's Gears of War has sold over three million units worldwide since release just over ten weeks ago...Xbox Live content for the Epic-developed title has reached 1.5 million downloads, with the most recent multiplayer maps released on January 10 totalling 750,000 downloads so far...The game was the best-selling title in the US on any platform in December, and has become the fastest selling Xbox 360 title since the console launched.

Meanwhile, Kotaku reports that Gears is selling out in Japan, despite the fact that it's American made, on the Xbox, and has really bad art direction.

I'll admit that I started playing Gears expecting to hate it. By the time the game wrapped up, though, I was hungry for more. Epic has accomplished nothing short of moving the classic 2D side-scrolling shooter genre (Contra, Metal slug, Gunstar) into 3D. It's a great game, and I'm glad that these sales figures will let them make more.