The date on the story is 11:15 AM CDT, September 30, 2008. Did they link to it from a current story?
There is a story posted today, but it speculates that Palin's reaction to Letterman's remarks may boost his ratings. It links to an earlier story about Palin rejecting Letterman's offer to appear on his show. There's a poll question on that one, and it's running well in Palin's favor.