CBS has announced the details of the April 12th episode, "The Wheaton Recurrence", which sees Wil Wheaton return as Sheldon's nemesis.
"The Wheaton Recurrence" - A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling, on THE BIG BANG THEORY, Monday, April 12 (9:31-10:00 PM, ET/PT) on the CBS Television Network.
You can find more information about the episode in our Episode Guide. A new episode airs next Monday, March 22nd, but then it's two weeks of reruns. On March 29th it is "The Adhesive Duck Deficiency", then "The Vengeance Formulation" on April 5th.