Being that this was a "Game Changer" regarding the 2008 presidential election, it appears a NYT insider finally revealed the New York Times did in fact cover up an illegal Obama-ACORN donor connection. Fearing disclosure of this crooked donor connection could have changed the entire outcome of the election, editors at the NYT chose to kill all ACORN-Obama related stories.
Excerpted From the Newsbusters Story:

“Upon learning this information and receiving the list of donors from the Obama campaign, Ms. Strom reported to Ms. Moncrief that her editors at The New York Times wanted her to kill the story because, and I quote, 'it was a game changer.'"... plus ...
During the ACORN Election Fraud hearing Representative James Sensenbrenner (R, Wis.) scolded the Times for its partisan bias in the news.
"If true, The New York Times is showing once again that it is a not an impartial observer of the political scene," he said. "If they want to be a mouthpiece for the Democratic Party, they should put Barack Obama approves of this in their newspaper."Also excerpted from the article:

The Wall Street Journal's John Fund had an excellent article last October detailing the connections between Operation Vote and the Obama campaign.
The Obama campaign denies it "has any ties" to Acorn, but Mr. Obama's ties are extensive.
Read Entire Story-Newsbusters