Cruise, along with JJ Abrams, will produce the movie, though Abrams won't be directing, as he did for Mission Impossible III. That job is still open but screenwriters have already been hired and the idea has been pitched by Cruise himself. Over the Summer, Abrams said that he and Cruise had a "really cool idea" for the fourth film.
This should be a blockbuster of epic proportions, since each movie in the Mission Impossible franchise has only gotten bigger and better, and Cruise definitely shines as an action star. Are you pumped for another chapter?