Realized a while back - the only people school firewalls keep away from resources are the teachers - students know of every proxy server on the planet (or create their own at home if needed).
Should the focus shift WAY to the "Acceptable use" side and away from "blanket blocking" of every useful sites online? What happens when WIMAX and other large area wireless broadband technologies are main stream and there is no single "pipe" schools can block?
The tendency is to show the frustrated teacher who cannot access Youtube video resources the very tools (vtunnel ect.) that the students are using to update their Myspace accounts while at schools.