Man.... I dont trust anyones figures on GTA4 PS3 vs 360 sales...
"Chart Track issued corrected figures for first day sales for GTA IV saying the title sold 631,000 copies by close of business.
This single day figure is almost as much as the previous sales record holder, GTA: San Andreas, managed in its first week - 677,000 units.
Sales for GTA IV were almost evenly divided between the two consoles on which it is available.
Chart Track said that 55% of sales were on the Xbox 360 and the remainder on the PlayStation3."
http://news.bbc.co.uk/1/hi/technology/7387310.stm
And thats bearing in mind that the 360 has more of the UK market...