web2.0 Tools in the Seinfeld Environment

Until last summer I had zero idea what web2.0 meant. But a summer class at George Mason University and over a year of practical application I think I'm getting a glimmering of an idea of what they mean. Probably the biggest impact is that these tools enable the common user to post content directly to the internet without the intervention/cooperation of an IT professional. That is powerful, and to some scary. It certainly taxes our leadership as we now must educate our people on responsible posting.
It is all about wikis, google applications such as google documents, blogs, twitter which is simply microblogging, social networking sites such as facebook and myspace, and even Zotero citation management software application. And don't forget Second Life and There that feature virtual 3D environments. Can't wait to teach my first class in Second Life!
The social nature of these tools is huge, now we can affect the social contact in the online world that somewhat resembles face-to-face interactions. What is your opinion on these tools, should we be using them, encouraging their use, or shut them off from our population?