There are currently no plans to release full games episode by episode on the Xbox 360, but don’t be surprised if that plan changes, or expansions and updates are released through Xbox live.
How would you like a game where if you buy the next episode, you are able to continue to places where your friends who did not buy it cannot, earning yourself new items, upgrades, and even new features, such as new in game music and whatnot. I think that would be both fun, and annoying, but it might be what is in store for some games as Xbox live and the Xbox 360 hard drive bring these capabilities to the game industry.
These episodes would help bring more excitement, and tension as each new episode is released, much like a television show. It also allows for longer hype as you might see a commercial detailing the next episode of Desperate Housewives, and then a commercial for the next episode of Perfect Dark Zero 2.