It was only a matter of time, that's why I bought a PS3, did everyone forget the games that were on the PS2? (not talking about 3rd party).
After 2 and half years developers are getting quite use to the PS3 so it should be less and less problematic to work on (wasn't the PS2 really hard to develope games for when it first came out aswell?)
The Cell and Blu-ray helps a lot
The userbase is much larger and obviously will keep growing, even at the price the PS3 is at it's still managing over 150,000 a week. Can you imaging what a $50 or even $100 price cut will do for sales?
Developers see the potential in the PS3 because of MGS4, Killzone 2, God of War III, Infamous, Heavy Rain etc.
Edit: And about the money issue, It's a huge multi-billion dollar company, you don't think they can throw away 10 - 15 million to make a game that will probably make then 20 - 30 million? Right now there making most of there money off the games, so it makes sense for them to get as much games out there as possible.