Oscar winner Lupita Nyong'o, who's been rumored since almost day one of casting, and Gwendoline Christie, who plays Brienne of Tarth on Game of Thrones and will soon be seen in The Hunger Games: Mockingjay as Commander Lyme, have been cast. This is either an example of JJ Abrams reacting to the Internet at large, or the Internet at large having totally jumped the gun with insta-complaints.
And given the fact that Nyong'o has always been talked about, and JJ has never shown any indication that he gets what people don't like about him...I'm betting the latter. Not that the Internet has ever been known to do that before.
Full press release at StarWars.com.