There is no need for this. All of Sony's internal developers have their own engines, and all are constantly working together to improve each other's engines, by sharing various tricks, tips, and methods.

Guerrilla has mentioned that they have received assistance from Naughty Dog, Insomniac, Sony Santa Monica (who they referred to as "the God of War guys" lol), and others on their engine, and they have in turn helped out studios like Naughty Dog with their engines. Naughty Dog used a method from Guerrilla to decrease flickering shadows in Uncharted, for example.

@makingmusic yes i thought uncharted had excellent shadows compared to say cod4 which had terrible low res ones. Although i think bad company had some flickering shadows...
Id say that uncharted 2 engine would be the equal of kz2 engine tbh

GOW 3's engine is probably better than KZ2's ATM

Well the only issue is whether Insomniac can code a game for that engine so quickly, I would guess they can make a game quicker on their own proprietary engine. I would still call NDs engine as good. The lighting and water effects are incredible

I'd reply to some of these posts now, but I gotta go and study for some test... I'll do it tomorrow =P