First, I'd like to understand how librarians failed to get control of school and district web filters when they arrived five to 10 years ago. This was a major strategic disaster for everyone involved, and both our schools and the profession of "school librarian" may simply never recover.
If we are going to recover some semblance of freedom and sanity in web filtering, librarians need to go on the offensive. They need to choose their ground carefully, and attack where they are strongest and the brainless blockers are weakest. Wikipedia is not that point. We need to push back where our Constitutional protections are strongest: political speech. Right now, I know that the Providence School Department systematically blocks political blogs. I'm sure that is not the only district doing that. We need a campaign to show we can successfully push back in a nationwide, coordinated fashion. Once that happens, we can think more about what is reasonable on the margins, like the "Dirty Sanchez" entry in Wikipedia.