Well, although the Ps3 has been selling more units recently, it's not like the Ps3 is outselling by a 2-to-1 ratio or anything like that. The X360 has pretty much kept up with the Ps3 sales, and add the what, 5M lead, and I would think the 360 would beat the PS3 to 30 million, but unsure about 50 million...
Enjoy