The nine grandmasters (including the world's top four: Carlsen, Anand, Aronian, Kramnik) played a fun exhibition game against "the rest of the world" on Twitter. The geniuses won easily, but they missed an amazing combination (checkmate or win of queen) in the position below:
Black to play and win quickly
Follow this link for the answer, the entertaining game, and the notes.
Follow Round 1 (right now!) at the official site, WhyChess, The Week in Chess, or your favorite paid provider.