What is an unconference?

Scripting News Annex: "The idea for an unconference came while sitting in the audience of a panel discussion at a conference, waiting for someone to say something intelligent, or not self-serving, or not mind-numbingly boring. The idea came while listening to someone drone endlessly through PowerPoint slides, nodding off, or (in later years) checking email, or posting something to my blog, wondering if it had to be so mind-numbingly boring." [more]: