Minecraft is selling at a good clip, shifting between 40,000 and 60,000 copies a week – it's just below Call of Duty: Black Ops 2 and Halo 4 in the weekly Xbox Live activity charts. As of November's end, total XBLA sales are at 4,476,904.
This is data according to Mojang itself, as reported by Gamasutra. This would indicate the Xbox Live Arcade port has exceeded half the total sales of the PC version, which reached the eight million mark back in the middle of November. Minecraft version 1.5 will be released in January.