Browsespace and Schoolboredom are two sites that have sprung up to provide access to Myspace via a proxy server. In a nutshell, pupils can use these sites to completely bypass their institutional firewalls.
Expect many more like this to spring up at least as fast as they can be blocked; enforcing DOPA is going to prove more difficult than legislators appeared to realise. If people want to access the site, they will. An outright ban does not constitute a solution.