Define Twitter in 140 Seconds Contest

Wayne Sutton has created the "What Is Twitter in 140 Seconds" contest. The idea is to create a video library of Twitter users who answer the question, "What is Twitter?" There's a variety of prizes including an iPhone and an iPod.  You have until June 23, 2008 to enter. Here are the rules:

1. Create video 
2. Video must be less than 140 secs.
3. Video must be tagged: whatistwitter
4. Submit video via form or hosting site.
5. Tweet #whatistwitter along with video url  

Wayne has created a video explaining the contest:

Here is an example video from Tara Hunt:

Update: Nate Westhimer points us to WTFisTwitter for more video definitions.