From a December 18 entry on PolitiFact.com :
Of all the falsehoods and distortions in the political discourse this year, one stood out from the rest.
The claim set political debate afire when it was made in August, raising issues from the role of government in health care to the bounds of acceptable political discussion. In a nod to the way technology has transformed politics, the statement wasn't made in an interview or a television ad. Sarah Palin posted it on her Facebook page.
Her assertion - that the government would set up boards to determine whether seniors and the disabled were worthy of care - spread through newscasts, talk shows, blogs and town hall meetings. Opponents of health care legislation said it revealed the real goals of the Democratic proposals. Advocates for health reform said it showed the depths to which their opponents would sink. Still others scratched their heads and said, “Death panels? Really?”
The editors of PolitiFact.com, the fact-checking Web site of the St. Petersburg Times, have chosen it as our inaugural “Lie of the Year.”
PolitiFact readers overwhelmingly supported the decision. Nearly 5,000 voted in a national poll to name the biggest lie, and 61 percent chose “death panels” from a field of eight finalists.