The Verge's gaming site, Polygon, received word direct from Telltale that "the five-episode series would not be the only games set in the Walking Dead universe that the studio plans on creating".
Along with the news of additional games by Telltale set in the Walking Dead universe, they have also announced plans to give the first five episode season a disc release to retail outlets in North America after episode five is released.
Activision also announced today that they are publishing an unrelated The Walking Dead game (confusingly called The Walking Dead Video Game), which will be developed by Terminal Reality (the developer's of Kinect Star Wars and Ghostbusters: The Video Game). Terminal Reality is basing their game on the television series rather than the comics (the latter is the universe Telltale's The Walking Dead is set in). It's going to be a first person shooter, though there is supposedly a limited amount of ammo and options for stealth available as well.