The Orion mailing list is very active. A good place to engage with developers. Orion has participated in a successful Google Summer of Code project and also has 3 UCOSP students working on term projects.
Orion continues to build the contributor list (55) and has added new committers from SAP, IBM and independant students in the 4.0 release.
Orion has a 4.0 Tutorial scheduled for EclipseCon Europe 2013 and presentations on our User Interface development, how to consume Orion, Sponsored Talks from SAP and IBM, and project integrations with Orion.
The Planet Orion blog remains a great place for news and tips/tricks on consuming Orion.
The New & Noteworthty link will be updated post release. There are already Milestone N&N posts.