I couch my comments in the context that I am an LMS administrator in the United States. One of the fundamental flaws with faculty choosing and using Web 2.0 technologies is that there is no administrative oversight by the institution. This may sound like a blessing, but from a legal standpoint, it puts the institution at extreme risk and often unnecessarily exposes student information to public scrutiny. Also (again, within the US), everything a student submits as part of a course immediately becomes a part of that student's academic record and must be available to institutional administration for purposes of disputes and must be protected. Having someone on staff to advise on these issues is a must.