Rovio Mobile, the developer behind Angry Birds, has stated that Xbox Live's antiquated system is the only reason that people can't currently enjoy the game on Xbox 360.
According to Peter Vesterbacka, Angry Birds' franchise manager, Microsoft won't allow them to frequently provide their users with content updates:
"Is that our fault? No, that's their problem. There is no reason why, when you do digital distribution on console, you couldn't do frequent updates. It's just a legacy way of thinking."
Angry Birds can be found on the PlayStation Network, where things aren't as restrictive. A version for the Nintendo 3DS is also in the works.