In an announcement on their blog, developer Almost Human has officially announced the development of Legend of Grimrock 2. It hardly comes at a surprise, considering the success of Legend of Grimrock.
Though the team was initially planning to create more downloadable content for Grimrock, it "simply would not have felt right" to them, so they opted to go on with a full fledged sequel. The added benefit to this is that a lot of content is already finished since it was planned to be part of the DLC. So technically, not only is Legend of Grimrock 2 announced, but it's already got a head start on development!
Did I make it through a Legend of Grimrock post without saying Grimlock instead? Yes? Excellent.