After six weeks, New Super Mario Bros. Wii is sitting pretty at about 8.6 million units sold. It will reach 10m very quickly, but the question is how quickly.
The current record holder is the PS2 version of Grant Theft Auto: Sand Andres, which, I believe, took 10 weeks to reach 10 million units sold.
So, New Super Mario Bros. Wii would need to break 10 million in three more weeks to break San Andreas's old record and become, by this particular metric, the fastest-selling single-platform game of all time.
Can it do it? Will it do it?
Edit: Seems like San Andreas reached it in nine weeks.