In fact, I posted a query about this to the opensolaris-arc mailing list today, and I got back an interesting automated reply:
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So, OpenSolaris ARC is dead. This has ramifications that go beyond just ON. Because there are other consolidations that we were promised were going to continue to be developed in the open: JDS, X11, and the pkg-gate. If the decisions for these technologies are no longer being made openly, or even the opinions being made available, then this makes Oracle's promise to continue to work with the community on them seem hollow.
So, what's left for "OpenSolaris" as so named? There are some code drops still being made. How long will that keep up? Are they continuing to take contribution from external parties? (I don't work on those gates, so I don't really know.) I'd like to know if the other consolidations have shut down too. At least the key decisions relating to those consolidations seem to have moved behind closed doors.