The Image Comics Expo took place this past weekend and Robert Kirkman was on hand to promote his line of comics, including The Walking Dead. During a live panel, Kirkman talked about The Governor in season 3, confirmed Merle's return, and mentions the upcoming video game:

"Kirkman commented on the casting of David Morrisey as the Governor for season three, and how he was present at Morrisey’s screentest. Kirkman had to struggle not to make faces at him to relieve his stress. AMC has yet to give any notes asking them to make massive changes, which has surprised Kirkman as he’d thought several times that he’d gone too far."

"...T-Dog is not Tyrese, clarified Kirkman, and he will be getting more character development as the season progresses. Merle will be seen again."

"The upcoming Walking Dead video game was the next topic of discussion. Telltale Games approached Kirkman, and managed to convince him to let them have a shot at the franchise when they explained that they weren’t interested in yet another game where people kill zombies, but in doing a character-driven game about survival. There are levels where you have to protect someone and only have so much food and have to decide if you will steal food from others and thus likely condemn them to death. Which characters live or die is something that will change in every playthrough depending on the player’s choices, and thus you can get a different experience each time you play. The game will incorporate new characters, bits of backstory from the comic, specifically focusing on Glenn in Atlanta before he joins the main cast."

Thanks to Bleeding Cool for their write-up of the event. You can read more at: http://www.bleedingcool.com/2012/02/27/the-walking-dead-alien-invasion-that-never-was-robert-kirkman-at-image-comics-expo/