Matthew Lasar has the details at Ars. This actually seems fairly obvious, in retrospect, similar to the sort of public access to the internet we are already accustomed to finding in libraries. There is a safety element, though, that limits access to non-operational hours. While I am skeptical of the sort of parenting that I feel leads to exaggeration of threats on school grounds, I think there is another good reason for this limit. Those resources should be prioritized for the students, of course, and not be in contention during the school day.
To be honest, I’d just be happy of the schools that have wireless open that up since that could potentially be used without even entering school grounds.