I think several things.
1) It's the day before Dec 22 and the day after Dec 20, 2012, and that when written out numerically, it will look kinda cool - 12/21/12, or 21/12/12, depending on if you're a month or a day first person.
2) I think it's the day that the Mayans happened to stop writing their calendar. Let's face it, no matter how far in the future you go, eventually, they all end. Every yr, mine stops on Dec 31. Doesn't mean there isn't going to be a Jan 1. Well.... except for Jan 00... ;-)
3) There are going to be a lot of very relieved, disappointed, or surprised people (depending on their personal response / actions to their belief that the world will end that day), when they get up in the morning. (Which begs the question - end at midnight ON the 21st, or GO to midnight, ending just before the 22nd... hmmm - they might have a stressful 24 hrs...)
Other than those thoughts, I don't think much about it :-)
at 12:13 AM on May. 3, 2011