10:46am: The Tigers and Leyland have officially announced that he is stepping down as the team's manager. At his press conference, Leyland said that he will likely accept a new role with the team that has yet to be determined (via John Lowe of the Detroit Free Press on Twitter). Leyland told GM Dave Dombrowski in September that he was running low on fuel, and though he was asked to return, he declined the offer (also via Lowe).
8:51am: The Tigers have scheduled a press conference for 11:30am ET today, and Tom Mazawey of Detroit Sports 105.1 reports that it's likely to announce that Jim Leyland will step down as the Tigers' manager (Twitter links). Mazawey adds that Leyland informed the team of his decision on their flight home from Boston. According to Ken Rosenthal of FOX Sports, the 68-year-old Leyland feels that it's time for someone younger to manage the team (Twitter link).
Leyland has managed the Tigers since the 2006 season, winning exactly 700 games against just 597 losses. In his time with Detroit, he's led the team to four playoff berths and twice reached the World Series. He came within a game of a fifth playoff appearance in 2009, but the Tigers fell victim to a late surge from the Twins and saw their season end in a Game 163 walk-off in Minnesota.
Despite the fact that he didn't win a World Series with the Tigers, Leyland does have a World Series ring after leading the 1997 Marlins to the Fall Classic and emerging victorious. A three-time Manager of the Year recipient (1990 and 1992 with the Pirates as well as 2006 with the Tigers), Leyland has a career record of 1769-1728. The Tigers' current stretch of three straight division titles marks the second three-year stretch of first place finishes in Leyland's managerial career. He accomplished the same feat with the Pirates from 1990-92.