The dow first broke the 10,000 point barrier in March of 1999. There was much celebrating. On October 6, 2008 the Dow Jones Industrial Average crossed the 10,000 point mark again, but this time on the way down. In honor of it closing below 10,000 for the first time in years, the next day we had another DOW 10k party. It wasn't quite as festive. Hopefully we won't have to have a dow 5,000 party.
This is reminiscent of when the dow hit 1,000. I looked it up since I don't personally remember it. The dow first closed above 1000 in November of 1972. The last time it closed below 1,000 was in late 1982, a full 10 years later. We are about 9.5 years after the first close above 10000 and it seems likely that we have at least another half year, so we will probably beat the 1,000 record. So far, it hasn't been as bad though, after hitting 1,000 there was a horrible bear market and the dow bottomed at 577.