First cheat code has been discovered.
Spawn helicopter:
PS3: O, O, L1, O, O, O, L1, L2, R1, Triangle, O, Triangle
Xbox 360: B, B, LB, B, B, B, LB, LT, RB, Y, B, Y
Looks like Rockstar has gone back to the button entering technique. I like that a lot. It allows me to get the cops off my back more easily while tearing down the highway.