Policy here is staff & students have the same access (or not) to our filter's 'content groups' so that if a teacher directs a class to a link, they know it is going to work. Preparation is the key, as long as they have checked the link works before the lesson, any problem sites can be amended beforehand. If, however, a request comes in mid-lesson that is "affecting my teaching" then the teacher only has themselves to blame.
Staff are allowed access to some relevant sites that students are not, youtube...streaming music...bbc iplayer etc. No access to webmail accounts is allowed for any users of the network. All correspondence coming from the site must be traceable.
The SLG and I can see no case for the use of social networking sites at this time. The amount of time wasted on them outweighs 100x any benefits they bring. The functions they provide (collaborative working etc.) are recreated with a properly functioning VLE.
EDIT On a related but OT note: During internet safety week an ICT teacher here did a presentation to staff around internet safety policy. It was found that many staff have accepted their students as friends/contacts on websites such as facebook. After discussions between staff, SLG have asked all of these contacts to be removed and any future requests declined due to the issues that could possibly arise.

