Marvel Studio’s Kevin Feige has confirmed that a Doctor Strange movie will be part of Marvel’s Phase 3.  Phase 2 will include Iron Man 3, Thor: The Dark World, in 2013, Captain America: Winter Soldier, Guardians of the Galaxy in 2014, and culminates in The Avengers 2 in 2015.  The only film in Phase 3 that has an announced debut date is Edgar Wright’s Ant-Man, which is slated for November 5th, 2015 (see "Disney Slates 'Ant-Man' Movie for Nov. 5, 2015").
But in talking with MTV Splash Page Feige, when asked about other films in Phase 3, stated "Doctor Strange, which I have been talking about for years, is definitely one of them."  Feige claims that Doctor Strange meets the criteria that Marvel Studios has for its maturing line of films, "He’s a great original character, and he checks the box off this criteria I have: he’s totally different from anything else we have, just like Guardians of the Galaxy.  He’s totally different from anything we’ve done before, as is Ant-Man."