We're already working on Mass Effect 3 right now. We do want to develop it in concert with listening to the way people are experiencing Mass Effect 2. We've got a lot of DLC coming out for Mass Effect 2 that we're also working on, and then we'll kind of blend that into developing and finishing Mass Effect 3. We don't want to take forever with it. We want people to be able to conclude this trilogy that have been with us over the years... [Development will be] along the same kind of time frame as Mass Effect 2.
It's tough to say how long we'll continue to do Cerberus Network in terms of the free content, for example. When you get Cerberus Network you get all this free stuff that's been released. On an ongoing basis we plan to have the whole spectrum, from a free item all the way up to paid stuff and potentially larger packs that tell a big portion of the story. And we want to do that in a way that connects Mass Effect 2 to Mass Effect 3. I think we'll be pretty close to the release of Mass Effect 3 before we really start focusing on that as the next story.
Source: http://multiplayerblog.mtv.com/2010/01/21/bioware-expect-mass-effect-3-in-late-2011early-2012-plenty-of-dlc-between-games/
