CBS's 60 Minutes presented documents the other night purporting to be memos written by George Bush's commanding officer in the National Guard and suggesting that, among other things, Bush had disobeyed direct orders. Now it turns out that the consensus among documentarians is that these particular documents are fraudulent. CBS is sticking to their story, however, so it'll be interesting to see how this plays out.
Meanwhile, readers who are interested in the story and curious as to how the documents were determined to be fraudulent can go here and here.