Partial list I'm considering:
1) Work 'appropriateness' into the grading requirement. Consider defining this. In other words, if commenting on a picture or piece of writing is required, then make only acceptable comments count. Others will be deleted.
1a) Possible appropriate definition: Plain english, no slang that discusses or gives feedback on the work in quesiton but doesn't attack anyone personally, asking questions is great and sharing opinions even better. Realize feedback that is not in person can be misunderstood.
2) Refer to students and colleagues by first name only. If people choose to self identify with more information then that's fine.
3) Moderate comments and postings to some degree, either by turning on moderated comments or by having comments emailed to you for your review.
4) Review NHS's acceptable use policy and make sure folks follow this.
5) Review some kind of 'using the internet safely' type of document - where to find this?