Chances are that quite a few of them have blogs of a sort already, and know how to make them using outside tools (myspace, nexopia, wordpress.com etc) and can share the how-to with their classmates. Those blogs aren't sponsored by anyone. I'd be tempted to leverage that, somehow. It would make evaluation a little more difficult with the having to go to different sites for each student, but it does bypass the district's enforced ignorance of where the Web is headed.