It seems that Halo 3 has hit new records in sales. However this figure is from Microsoft themselves.
The staggering figure presumably came from Microsoft’s internal estimates.
Apparently Halo 3 has outsold every entertainment release in history and is making and breaking sales records all over the world. Oh great, Microsoft should stop making OSes and concentrate on making games instead. I guess this is going to be where the bulk of the revenue is going to come from for Microsoft.