Usually "we" as in who? If that's so then God of War 2 is also a PS3 exclusive, since it's playble on both systems that has a sony brand on it... The term exclusive is typically put on a game that cannot be played on anyother console during that time. Zelda was playable on both Wii and Gamecube, there was no need to get Twilight princess on the Wii.
"Yes, but if we go by that, then 360 has one of the best lineups, ever"
Isn't that what microsoft constantly tells everyone? the 360 does technically has one of the best holiday lineups ever, but line-up and library are two different things. With library being much more important.