According to the latest Gallup survey, Mitt Romney is polling 52% of likely voters. At this point in the race he is ahead of:
Where Jimmy Carter was in 1976 (47%)
Where Ronald Reagan was in 1980 (39% — Carter was six points up)
Where George H.W. Bush was in 1988 (50%)
Where Bill Clinton was in 1992 (40%)
Where George W. Bush was in 2000 (48%)
Where Barack Obama was in 2008 (49%)
UPDATE: The latest (Oct 21) Gallup numbers show the trend continues.