As far as I know, the consortium who originally created and backed OpenSocial is pretty much dead. That doesn't necessarily mean the standard is "dead dead" though. Some products still implement it and there are still products coming out that will support it. I can say this because we're working on one of those products at Fogbeam Labs.
Sadly the open-source reference implementation, Apache Shindig, fell into a state of inactivity to the point that the ASF project was moved to the Attick, but the code is still available and can be forked anytime.
Likewise for the standard itself... if people are interested in this sort of thing, a group can always create a new version of the standard, or - depending on copyright / license / blah - create a successor standard.
If anyone reading this is interested in either Shindig or the OpenSocial spec, or both, feel free to drop me a line at prhodes@fogbeam.com. I'd love to keep in touch with anybody still interested in / working on stuff in this area.
Edit: just found this:
https://www.w3.org/blog/2014/12/opensocial-foundation-moves-...
Looks like anything current going on with OpenSocial is here now.
https://www.w3.org/Social/WG