[like fragmented email conversations] ... Twitter-like systems are also difficult to follow - the tools so far do not do a great job of isolating conversation threads, manage/filter messages over time, etc. On top of this - do we really think that companies will have wide-open conversation spaces without applying permission models that limit access rights based on a variety of business reasons? I don't disagree with the concept of transparency - but you have to consider policies related to role, separation of duties, security, confidentiality, intellectual property, compliance and so on. There are very good reasons to have bigger walled gardens within enterprise organizations - and some organizations will be much more public than others - but we do get back to addressing barriers encountered by other messaging tools.

BTW - many (if not all) of these concerns and issues apply equally to "activity streams". The need for activity streams to support permission models, and comply with logging/audit/compliance/discovery requirements should be pretty clear. For vendors offering "Twitter for the Enterprise" or "Activity Streams" - making sure you support security (permission/access controls), identity, and records management requirements has no down side. - Mike Gotta