On the face of it, the concept of Twittering didn't really make too much sense to me. I mean, only 140 characters per post didn't seem like anything worthwhile. However, after hearing about how awesome Twitter was from all of the various podcasts I follow, I decided to sign up and take a look to see what all the hype was about.
We can sum it up by saying that constraint drives creativity or some such. But the coolest thing, at least for me, is that Twitter offers fairly simple integration with so many other web-based services that it makes it super simple to keep all of the places where you web up-to-date.
Of course, maybe it's just popular because it allows people who crave attention to mingle with other people who crave attention. A perfect platform for mutual ego stroking. But, upon second thought, I'm sure that has nothing to do with it.
If you don't know what Twitter is, check out this great video created over at Common Craft.