Every four years, the Royal & Ancient Golf Club of St. Andrews and the United States Golf Association get together and make any necessary changes to the Rules of Golf. There are several changes for this year, most notably the definition of addressing a ball and a ball moving after address. A player is now considered to have addressed the ball if he has grounded his club, either in front of or behind the ball.
Last year, Webb Simpson famously had his ball move twice on putting greens after addressing it, resulting in one-stroke penalties both times. In both cases, Simpson had nothing to do with the ball moving. The Rules have been amended to say that a ball that has moved after addressed, but where it is known or virtually certain that the player did not cause it to move, does not result in a penalty and the player must now play it from its new position.
For a complete listing of the Rules changes for 2012, please visit Golf Canada at http://www.golfcanada.ca/rules/Rules-of-Golf-Changes-for-2012/