UPDATE: Some of this has been officially confirmed by Warner Bros.
This past weekend a story hit the web stating that the last film in the Harry Potter franchise, Harry Potter and the Deathly Hallows, will be shot as two films. While this story originally appeared in a British newspaper it has spread like wildfire around the internet. You may remember that a similar rumor appeared online while filming of Order of the Phoenix was taking place.
According to the article the reason given by an unnamed source is that splitting the two films is artistic rather than financial reasons. The article also states that Warner Bros. is rumored to be thinking of Steven Spielberg as director of the last movie.
UPDATE: Empire Online reports that the WB has let them know that "no decision has been made about Harry Potter and the Deathly Hallows" and that Steve Kloves will be returning for the last picture but that no script has been started due to the Writer's Guild of America (WGA) strike.