It involves sales and statistics compiled by the lovely folks at Gamasutra. Most specifically they are looking at the Playstation 3's best selling games so far in 2009. Please note these figures are correct in terms of US sales.
Exclusive title Killzone 2 sits atop the Playstation 3's best software sales charts. It edged out both Resident Evil 5 and Street Fighter IV who respectively took the second and third spots. Killzone 2 is estimated to have 750,000 copies in the US so far. Sitting in fourth place is UFC 2009 Undisputed which has been somewhat of a surprise hit since its release earlier in the year. Rounding out the sports title interest, MLB '09: The Show took fifth place.
Interestingly the XBOX 360's chart consisted of similar titles, with the only Microsoft published title - Halo Wars - taking fourth place. Nintendo's top five consisted of the usual suspects - Wii Fit, Wii Play and Mario Kart Wii.