Sony screwed up by touting the the PS3 as a super gaming computer, when all it is is a gaming console that had some cool extra's. Sure it has a lot of the same chipsets and graphics card as a top end gaming rig did when it was released, but now it's just meh. In hyping the system up so much they priced it way to high and the 360 and Wii capitalized on that by having a lower price point which meant more systems sold, which meant that games the developers might have considered for the PS3 only now became multi platform games because really it's about making money, and with more 360's and Wii's out there than PS3's (which are still hella pricey for less than what you get in a Wii or 360 Bundle of the same price) game developers have to decide if it's worth it to make a game console exclusive. If you want console exclusivity go get a Wii, it has more Wii exclusives than the PS3 and 360 combined x 5, but then the Wii is a completely different console than the 360 and PS3 are and it has an almost completely different demographic that it caters to.
The only thing that Sony has done right with the PS3 is make it and the PSP interact with each other (to a point) and the marketing of the systems and it's games is also more entertaining. As far as the PS3 exclusive games, those are mostly developed by 1st party Sony developers or 3rd party developers that have an exclusive partnership with Sony. Same goes for the 360, exclusive games are either developed in house or by 3rd party companies (like Turn 10 and Bungie).
Oh and whats up with Sony all but removing the backwards compatability, you can play PS1 games but not PS2 games, WTF. The 360 still plays 85% of all original xbox games and the ones it doesn't are either available for DL, have a 360 version available (like BF Modern Combat and The Godfather) or just really sucked.