Top Story of 2004
Such a story has to be both important and widely unexpected. Let me clarify the latter criterion. Some number of natural disasters occur every year, so while the specifics of SE Asia's tragedy were certainly unanticipated, the general pattern is not. Whether Bush won re-election or not, there was significant expectation either way.
No, Rathergate is my choice for story of the year. Yes, year after year we complain about bias and false information in the MSM, but who could have predicted that one of the big three anchors would fall so far so fast? A man planning some sort of graceful, eloquent retirement in 2005 decides to publish those infamous forged memos, despite the source and despite the questions even CBS's small amount of verification raised.
Dan Rather isn't stupid. IMO, he knew they were to good to be true, and very likely were at least unverifyable. IMO, Dan Rather parlayed what he assumed was his unassailable reputation with President Bush's indefensible record as he saw it. IMO, what Dan Rather counted on most was the brotherhood of the MSM protecting him, and many of his brothers are still trying. What he didn't count on was this new media force - the blogs, among them Minnesota's own Powerline.
Whether this affected the election we may never know. But this scandal clearly marked a watershed, where the bias of the MSM crossed the line on such a large scale that it forced the early, undignified retirement of a seemingly invulnerable MSM icon.