Yesterday, the Dow Jones Industrial Average closed at 11,011.90, above 11,000 for the first time since June 7, 2001. Reaching 11,000, while symbolic, is still signifigant as it is a sign that the markets are going in the right direction. A big reason for yesterday's gain was the stock of GM, which has took a beating last year but was given some positive reports from Goldman Sachs, causing the stock to go up 7.7%.
The DJIA is comprised of the 30 most widely held companies in the United States and first eclipsed the 11,000 mark in May of 1999 (oh .com boom how we miss you) and its record high was 11,723 in January 2000. On the first day open after September 11th, it lost 7.12%, which was also the Dow's biggest single day point loss. The biggest one day percentage loss was in 1914 when the Dow lost 24.39%.
More on the DJIA at Wikipedia.