OK, so it's only a number and the Dow is made up of just 30 stocks and the other indexes are still below their 2000 highs. Even so, it's a big number with three zeros at the end, so you can be sure it will be getting lots of attention. For the day, the Dow was up just 20 points. From this afternoon's NYT story:

The current rally, which started in late July after an early summer swoon, has followed a well-worn pattern in which stocks do well in the last three months of midterm election years, analysts experts note. The one difference this time is that the stock market started moving up in the third quarter, which historically has proven to be a weak stretch. "You have to back a very long way to find a negative” in a midterm election year, said Sam Stovall, chief investment strategist at Standard & Poor’s. "On average, you have a positive year 90 percent of the time."

Update: 12K milestone: David Gaffen at the WSJ's Marketbeat notes that this is the second-longest the Dow has taken between 1000-point milestones. The Dow first closed above 11,000 in May 1999. The longest it took was the 15 years between the first close above 1000 in 1972 and the first close above 2000 in 1987. And in a very weird coincidence, the 12,000 mark was achieved on Oct. 19, exactly 19 years after the 1987 crash.