From pg's essay "Hiring is Obsolete" (http://www.paulgraham.com/hiring.html),

  Have you ever noticed that when animals are let out of cages, they don't always realize at first that the door's open? 
  Often they have to be poked with a stick to get them out. Something similar happened with blogs. 
  People could have been publishing online in 1995, and yet blogging has only really taken off in the last couple years. 
  In 1995 we thought only professional writers were entitled to publish their ideas, and that anyone else who did was a crank. 
  Now publishing online is becoming so popular that everyone wants to do it, even print journalists. But blogging has not 
  taken off recently because of any technical innovation; it just took eight years for everyone to realize the cage was open.

There are quite a few web technoligies for which I could write your same sentence. What makes bulletin boards interesting is that anyone can become a broadcaster, except that not many people were aware of bulletin boards so you didn't reach many people. What makes electronic mailing lists interesting is that anyone can become a broadcaster, except they weren't that easier to discover and join so you didn't reach many people. What makes blogging+rss interesting is that anyone can become a broadcaster, except it has started to get a similar air of elitism as traditional editorials so unless you have some gimmick or are already famous you don't reach many people. What makes twitter interesting is that anyone can become a broadcaster, except the site has become so inundated with celebrities, news personalities, corporations and marketters that, like blogging, unless you have a gimmick or are already famous, you are just part of the noise and don't reach many people.

Is twitter interesting? Sure. Is it revolutionary? Eh, maybe a little. But does it represent some kind of fundamental shift in how people communicate and who can broadcast to large audiences? Not in my opinion. Twitter makes some things easier, but it doesn't completely change the game. There have been any number of amazing broadcast methods coming down the pipe ever since the web came into existence. But all that broadcasting for the average man doesn't make a lick of difference if no one is paying attention.