I am at present listening to a live interview with Doug Gresham on Middle-earth Radio. Mr. Gresham confirmed the rumor that Walden Media’s option for a fourth Narnia film has expired. For more about what that might mean, see Paul Martin’s article on NarniaFans.com at this link: More information on the Future of Narnia on Film.
Gresham also confirmed that he is in the very early stages of developing a full-blown stage production of The Lion, the Witch, and the Wardrobe.
At a later date, I will have more information about the interview, including a link to the promised recording of the conversation when it is available. You may be able to catch the tail end of the live broadcast if you are quick. Here is the link: Middle-earth Radio.