Ideas for a 5-minute speech on blogging/the blogosphere

Hello, fellow Netizens!

I'll be giving a short speech on blogging and the blogosphere on Friday and I'd like to solicit comments / suggestions for how to introduce the subject to a class of young people!
I've got Hugh Hewitt's "Blog", Glenn Reynold's "An Army of Davids" and I'll be checking out Harvey's "Bad Example" http://www.badexample.mu.nu/ and "Basil's Blog" ( http://www.basilsblog.net/ or http://basilsblog.blogspot.com/ ) for some backgroud.
Comments are appreciated!