In a post on the game's official web site, Age of Empires Online's executive producer Danan Davis said that Gas Powered Games has been working on the title for some time to develop add-on packs for the game. He states that the switch over has been in the works for some time and Gas Powered and its leader Chris Taylor "share our long-term commitment to make this a success." The reasons for the switch from Robot Entertainment, which has a number of people who worked on the original Age of Empires RTS games, are pretty vague with Davis saying only, "Our previous development partner, Robot Entertainment, did amazing work on the game, and we wish them the best in their future projects."
You may remember that Taylor recently told us that Gas Powered's previously announced game, Kings and Castles, was now on hold and it's now clear that its takeover of Age of Empires Online's development was the reason. Davis states that even with this switch in developers the game is still scheduled to launch later in 2011.
Update: In a post on Robot Entertainment's message board, the developer's community manager assures fans that this switch was in the works for some time, saying, "This was always in the plan. We've even had some GPG guys down to the studio to get them trained up as far back as last fall. When we opened RE, our goal was to work on our own original games. We announced Orcs Must Die! this morning, and will have more info on future games relatively soon ;) "
Gallery: Age of Empires Online Screenshots