Season 3 of HBO’s Game of Thrones will premiere on March 31st, according to the network.  The show, which drew 11 million viewers per episode on HBO during its second season (as well as 4 million pirated downloads, see "'Game of Thrones' Is Most Pirated TV Show"), drove big sales of games (see "Top 10 Board Games--Spring 2012") and comics (see "Top 300 Graphic Novels--June 2012") during the last season. As anticipation for Season 3 builds and the show starts airing, those sales can be expected to kick up again from their lower level between seasons. 
A number of new actors will appear in Season 3, including Diana Rigg of Avengers fame and Coldplay drummer Will Champion, according to Hollywood Reporter.  The new season will be drawn from half the material in A Storm of Swords.