People: The talkers, authors, contributors – empowerment of the individual.
Places: All the diverse venues the conversations can take place in.
Process: What collaboration (and moderation) you enable, how you entitle contributor types and how you integrate with existing systems.
Platform: Where and how you tie together the places, processes, people (identity/privacy) and privileges.
Patterns: Presenting, tracking, filtering, measuring, monitoring and decision support.