Before the real Virginia Tech Killer was identified, a Chicago Sun-Times columnist named Michael Sneed (female) posted a story on the newspaper's website citing sources claiming:

"authorities were investigating whether the gunman who killed 32 people in a rampage on the Virginia Tech campus was a Chinese national who arrived in the United States last year on a student visa."

This story immediately got picked up by Chinese media and bloggers, and went all over the Chinese Internet, as journalist and blogger Luqiu Luwei describes (original Chinese version of her post is here).  Then the Sun-Times goes and changes the original story multiple times, with various versions documented by Letters from China, China Point, and James Fallows (here and here), among others. They erased the original version of the story, as if it never existed, and it is now (as of this reading at 4:30pm Hong Kong time) replaced with a new version describing identification of South Korean student Cho Seung-Hui - with no mention or trace anywhere of the earlier version. Except that if you Technorati that article's URL you'll see lots of people quoted from it and blogged about it, and the original is also preserved in the Google Cache.

I agree with Fallows' condemnation of the Sun-Times' failure to acknowledge the mistake combined with what appears to be a strategy of pretending they never reported a massive piece of misinformation:

Amending information in real time is a virtue of the web. Covering up one’s tracks is not. Wasn’t this pretty much what Orwell had in mind with the concept of the “memory hole“?

For the Oneline Journalism Hall of Shame record, here is a screengrab of the original article taken from the Google cache (click to enlarge):