Even as the New York Times has the gall to claim "the pullout from Vietnam had few negative repercussions for the United States and its allies", Brent Baker opens up the legacy media's memory hole to remind the rest of us of "The Unnewsworthy Holocaust: TV News and Terror in Cambodia":

In the wake of President George W. Bush's reminder Wednesday about how the “killing fields” of Cambodia followed the 1975 U.S. pullout from Vietnam and the region, a look back at a study, by William C. Adams and Michael Joblove, which documented how from 1975 to 1978 the three broadcast network evening newscasts, as well as the New York Times and Washington Post, virtually ignored the ongoing massacre of millions by the Khmer Rouge. Below is an excerpt, fairly lengthy since I can't imagine this is online anywhere else, from the MRC's 1990 book, “And That's the Way It Isn't: A Reference Guide to Media Bias.”

That has always been the most important power of gatekeepers. Not in deciding when to open the gate, but in when to close it.

And that's the reason that the gatekeepers are so upset by the rise of blogs and other alternative media. They still have the ability to open the gate for stories they like, and to try to focus attention on those stories, but they no longer have the ability to close the gate because thousands of bloggers have dug tunnels under the fence.