Dangerously Irrelevant's "26 Internet safety talking points" is just about the best essay I've read on creating a sane, evidence-led, pro-education, anti-fear Internet safety policy for a school. Given that schools are third in line to receive oppressive technology mandates (behind autocratic nations and prisons, ahead of corporate enterprise users and the general public), this is desperately needed.
B. The technology function of your school organization exists to serve the educational function, not the other way around. Corollary: your technology coordinator works for you, not vice versa.
C. Mobile phones, Facebook, Wikipedia, YouTube, blogs, Wikispaces, Google, and whatever other technologies you're blocking are not inherently evil. Stop demonizing them and focus on people's behavior, not the tools, particularly when it comes to making policy.
You don't need special policies for specific tools. Just check that the policies you have are inclusive of electronic communication channels and then enforce the policies you already have on bullying, cheating, sexual harassment, inappropriate communication, illicit behavior, etc.
D. Why are you penalizing the 95% for the 5%? You don't do this in other areas of discipline at school. Even though you know some students will use their voices or bodies inappropriately in school, you don't ban everyone from speaking or moving. You know some students may show up drunk to the prom, yet you don't cancel the prom because of a few rule breakers. Instead, you assume that most students will act appropriately most of the time and then you enforce reasonable expectations and policies for the occasional few that don't. To use a historical analogy, it's the difference between DUI-style policies and flat-out Prohibition (which, if you recall, failed miserably). Just as you don't put entire schools on lockdown every time there's a fight in the cafeteria, you need to stop penalizing entire student bodies because of statistically-infrequent, worst-case scenarios.
E. You never can promise 100% safety. For instance, you never would promise a parent that her child would never, ever be in a fight at school. So quit trying to guarantee 100% safety when it comes to technology. Provide reasonable supervision, implement reasonable procedures and policies, and move on.
It starts at A and goes all the way down to Z. Every one of 'em's a gem.