Barcamp Los Angeles co-organizer Kareem Mayan has posted a useful comparison between his experience at ETECH and Barcamp:

So if information is easily accessible on the net, and value comes from conversations about that information, why pay $1k+ to attend a large conference IF those attendees could just as easily attend a locally organized, self-programmed conference?
I don’t think big conferences are going away anytime soon, but the Unconference model is taking off. Check the Barcamp page or the Barcamp blog–in the last week alone there are posts about unconferences happening in Minnesota, Houston, San Diego, Austin, Toronto, Prague, Ottawa, Washington DC, and Oklahoma City.

It makes sense, really. The Barcamp model fuses community and knowledge transfer, is inexpensive to run, and is driven by passionate people. How can it fail?