Some quotes from How Good Is The Mainstream Media At Linking Out? (via The Exploding Newsroom ):
We believe that linking to useful websites doesn’t “leak” traffic – quite the opposite in fact. Offering useful links actually makes visitors more likely to return to see what other interesting websites they might find in the future, a model that sites such as Digg and Fark are built around.
Of course as a blogger it’s sometimes hard to appreciate the fact that mainstream media websites are, with the exception of the BBC, business entities with shareholders and an obligation to maximise profits. It’s understandable that they are reluctant to send valuable page views elsewhere. We spent some time researching the issue to see if there was a correlation between the frequency a site links out and the number of links it gets in return.
The resulting figure of 0.842733801 shows that in general there is a strong relationship between news websites linking out and getting links in return.