In the console wars, Microsoft has one big advantage. Like Apple's iPhone, it only had the one product, Xbox. Sony has to split resources between two, PS3 and Vita.
That will lead to some hard decisions. And we saw how Sony screwed up by ignoring the PSP after its launch to focus on PS3. Sure, it has promised not to repeat the mistake, but the company is losing money (there's a very good article on Sony's overall health here) and if it trims a couple of studios here and there may find itself in the same boat again.
Also, if a game is released by a third party on PS3, Vita and Xbox, the PS3 sales will look lower as some gamers buy the portable version. Then, Microsoft claims the win and Sony appears to be doing worse. How long before it politely asks for delays in Vita launches to not skew the sales figures?
I don't see any of these problems as major ones, but it only takes a slight perception of failure or weakness (BlackBerry's recent troubles anyone?) in the eyes of consumers or publishers for a product to be damaged.
Just a cheery thought for the weekend.