I think 2008's The Strangers really took a lot of people by surprise. It wasn't a game changing horror film, but was really intense, well shot, and reminiscent of a 70's horror film. Sequel talk started almost right after The Strangers hit theaters, but nothing ever became of it.
Finally, it looks like a sequel will start shooting this year. Multiple sources have confirmed that Relativity Media is having Laurent Briet directing a script from the original film's director/writer, Bryan Bertino. We'll have more information on this film, as it is released.