Real virtual communities

I was recently involved in discussions about Mission Shaped Church. When it came to considering modern concepts of community, I was particularly keen that the myriad virtual communities to which many of us subscribe should be taken seriously as forms of friendship and support. My experience has certainly been that I have been able to share honestly and with a degree of vulnerability with folk whom I have never met but with whom I feel a connection and whose wisdom and insight I value. On occasion I have subsequently met some of the folk, mainly bloggers, with whom I have shared and our relationship has taken on another dimension but the face to face meet is not vital to the sense of community and sharing that is possible. One such community is RevGalBlogPals. In this community I have obtained practical advice, shared pain and gleaned wisdom. My perception is that, often, the value of online communities is under estimated. In a profession as isolating as ministry, however, such networks can be life giving.
More recently I have enjoyed connecting with others on Facebook. I refuse to become involved in Mafia Wars or Farmville or other such time consuming activities offered. But I do love snooping around, seeing what friends are up to, checking out their pictures and offering comments. However I see this as a very different kind of social networking and one that requires a lot more care and discretion. And it concerns me that there is often too much inappropriate information volunteered. Many younger folk do not see that as a problem and I accept that their way of connecting and interacting is different and is perfectly acceptable for them. However I do get concerned when colleagues post details that could be misconstrued or that demonstrate a lack of professionalism and are seemingly unaware of the very public nature of such a site.
Like all online communities, candour and discernment must be employed for our own protection as well as for the protection of those we serve.
I would be interested to know how others work out what is an appropriate level of sharing and the safety or otherwise of online communities.