@OP
If you're talking about significance for each system :
TO ME, Right NOW, PS3 main games are Metal Gear Solid 4 and Killzone...
Other rightful candidates are Gran Turismo Prologue, Uncharted, Littel Big Planet and Resistance series.
Of course there's more to come:
*Gran Turismo 5 (full game) it's the biggest PlayStation franchise, period.
*God of War 3 (it became a major franchise late in the life of PS2, but its significance for PS3 and its awesomeness will be tenfold)
*Final Fantasy XIII and XIII versus. Even if XIII is no longer exclusive outside of Japan, the Final Fantasy name is still VERY much a PlayStation flagship. Versus XIII will definitely be a very prestigious game to grace the PS3 library.
*Untitled team ICO game. Another first-party title of great importance and also another game from a team that developed a masterpiece in the late life of PS2. Shrouded in secrecy still, only the very knowledgeable gamers have their eyes set on this one at the moment, but when its time comes it'll definitely be a shining star in the PS3 library.
