It was true after E3 2008, certainly. But there has always been a shifting network of alliances, at least from my perspective. Throughout 2006 and early 2007, there was the "Wii60" mentality, that the two platforms could perfectly complement each other, and that the Wii60 owner represented the true gamer, dividing between either Wii60 or a Sony fanboy. Of course, that alliance kinda fell apart when the stark contrasts between Wii and 360 really came out, and as Wii simply pulled away to where the 360 could only hope to go.
After E3, the idea was that PS360 together formed a gamers' paradise, and that they would save the industry, while Nintendo would destroy it, but that alliance started falling apart even sooner than the Wii60 one, with Sony once again on the receiving end of a lot of scorn, but Nintendo hasn't really come out of the doghouse either, possibly indicative of a looming Sony-Nintendo alliance
Of course, it's all pointless fanboy games anyway

Monster Hunter: pissing me off since 2010.







