If you want a simple and easy explanation of what twitter is you need to look no futher than this post from Dave Winer. The key take away for me from his post was monetization is something that will follow once you have a compelling product that has a viral following. Lastly, I feel compelled to post this cool snippet from the New York Times about twitter. Can't recall the last time I actually read out a telegram. Darn!, I feel like I should have saved those precious relics :)
TWITTER IS THE TELEGRAPH SERVICE OF THE INTERNET STOP IT LETS YOU BROADCAST SHORT MESSAGES ABOUT YOURSELF TO ANYONE INTERESTED STOP IT JUST RAISED MONEY FROM UNION SQUARE VENTURES STOP.