We all knew Gears of War 2 was going to be a huge seller. The news that Gears of War 2 has just hit the 3 million units sold mark should come as no surprise. After all, the game had already sold 2 million on its launch weekend. 1.5 million users signed on to Xbox Live to play the game. However, Gears of War 2′s Xbox Live run was cut short by the old reigning champ Halo 3 which quickly regained the lead a mere week later. To put the success into perspective, the original Gears of War took over 10 weeks to sell the same number of units.

[source: Xboxfanboy]