The Amazon [IMDB] spokesman claimed they get their info from studios. However when pressed, he admitted they were using 'published reports' (aka 'rumors') as the basis for their plot and cast details for Trek XI, and they couldnt even identify what reports they used.
The WSJ did try and get someone actually associated with Star Trek XI on the record regarding the Damon rumor, but neither Paramount nor JJ Abrams will confirm anything. They do quote Damon's publicist as saying: "No one has approached Matt". The Insider's Marc Malkin tells us tonight that he is still sticking by his source who says that JJ Abrams is interested in Damon for the role of Kirk.