Yeah MGS2 used the pressure sensitivity a lot, but I didn't notice any in MGS4 (like how you could lower your weapon instead of fire if you just eased slowly off the trigger.) I don't think they use it in LBP either, since you jump higher by holding the button longer and not mashing it harder. In fact, I'm not entirely certain that the PS3 has pressure sensitive buttons, although it seems like it would since it's, you know, an upgrade from the PS2.
PS: new level out. "Conveyor Challenge". Basically you navigate obstacles as they come towards you on a conveyor belt. Took me like 18 hours, so play it!
It's pretty fun playing random levels people have made online. I like to find the stuff with barely any plays and see what kind of shit has been come up with. Even though the vast majority are really crappy and unpolished, it's cool anyway because every level is different, and you never know what you'll see (people sure like to put rockets and ramps in their levels though.) The game really is like a journey into imagination-land.