Speaking here, Jeronimo Barrera, Rockstar's VP of product development has said that the upcoming Xbox 360 content for GTA IV, famously paid for by Microsoft, is a first step for the company into episodic development.
"We are calling the downloadable content (coming to the Xbox 360) episodes," he said.
But it's "an experiment" they're quick to add. Right now Rockstar doesn't seem sure that there are enough users with access to online content on the 360 to make it worthwhile for them to continue pumping out episodes.
There's a lot more stuff on Kotaku there from a GTA hands-on in New York. Take a look at this as well.