Dan Drezner and Anne Marie Slaughter are having a debate over whether realism or new liberalism better describe world affairs. It began with a column by Slaughter in the Atlantic, which led to this response by Drezner, and then this riposte from Slaughter. Very interesting reading for the IR set.
(Edit: This debate has legs. Since my original post, Drezner put up another post on the subject. Furthermore, Dan Trombly and Henry Farrell have written very interesting (and long) posts weighing in on the debate).