My mini conference topic

My mini conference topic will be looking at the process, benefits and restrictions in trying to develop an online forum for multidisciplinary maternity health professionals in a large organisation (my large organisation is QLD Health). I have come across many road blocks and am undecided about which platform to use, whether to use an existing one, whether to use an intranet site (only accessible at work) or use a well known, already established platform that will provide immediate numbers. My research so far has shown that despite people thinking it is a good idea, most people are reluctant to engage or are appathetic which means only a few select do, which stifles the discussion. I am concerned about confidentialty issues if I keep it just within the hospital and also this prevents network building and new ideas flowing in because everyone knows what everyone knows. Also I feel people don't really have the time to go online at work and so can see the benefit for an offline site. I would like to hold a synchronous event in Elluminate or Dim Dim if I like it better (will wait and see after tommorrow) I would like to invite people who have: tried to set something like this up and running in a large organisation, people who have engaged in a discussion forum like this and people who have facilitated a discussion forum - time it took, pros & cons. I would appreciate everybodies feedback and thoughts on this topic.