Desired features

Facebook-style social media with user profiles; activity timeline and status updates; friend feeds; blogging. For all FB’s downsides, it effectively engages people. Many find it enjoyable to use, and use it extensively.
Profiles with Karma (or alternative)
Green media aggregation (Google reader/Netvibes). Rich media: “GreenTube” (users upload clips detailing plans and experiences); CN Media: short films and adverts promoting the system and its initiatives. Focused on collaboration rather than noise.
High-profile video events: from debates and Q&As to lectures and thought seminars
Channels for OIC teams and links to OIC projects
Widgets to badge other social networks
Protocols: use OAuth – allow easy joining and connecting. This doesn’t allow for privacy, so DFRN (developed by the Friendika project) may be needed
Allow anonymous posting options? Or at least like blogs that allow posting with name & email address. As Wikipedia has found (along with many other sites), lowering barriers to entry encourages participation.
Use OStatus for status updates
Well supported, by active development community (essential, unless we score major funding)
Stable and ready for use, or very close. (We can support the development of other platforms, but need something to use in the meantime.)

The Catalyst Network (CN) has a hub, connected by links and feeds to the Open Innovation Platform (OIP) and the Green Knowledge Trust (GKT).

Contributors to GKT and OIP profiled on CN
Projects on OIP profiled on CN Media
Green problems in need of solutions identified on GKT, showcased on CN and OIP