What's the best game to get for online multiplayer co-op for xbox 360?

Is Borderlands good? Any better recommendations?

Borderlands is great, I've had tons of fun playing the pc version in co-op.

Borderland is awesome for multiplayer co-op.
Also try Splinter Cell conviction fo Co-op.

i would say the best is CoD MW2
but borderlands is a great game!!!! i really enjoyed playing it with my friends.. the hunter is the most fun class to play :D

The third installment in the cyberpunk action-RPG series is in the works at Eidos Montreal.