"The Stone Prisoner adds Shale to the game, a stone golem and a party member. Shale is a powerful character and has a back story, voice acting, and a unique quest. The Stone Prisoner also adds new locations and items. New copies contain a promotional code to received The Stone Prisoner for free, which was valid until April 30, 2010. The code does, however, still work for those who have not used it prior to April 30, 2010"
Source: Wikipedia, Dragon Age: Origins, available under the CC-BY-SA License.