Indeed I should give you all some more information about the current status of the project and its roadmap.
I am working in a full time day job, and I am working on Spring Social Google on my spare time, so my progress depends on the amount of time I can squeeze in. Currently I am focusing on stabilizing the Contacts and Plus APIs. Specifically I am working on adding search and pagination as requested here. During the coming week I expect to update Contacts and Plus APIs with search and pagination and reflect it in the example application. In response to your requests, I would like to make the project compatible with Spring 3.0, but given the need to prioritize, and since the project is still not in release status, I can't say when I will get to it, but hopefully it will be this month.
For the long term roadmap, I suppose the main focus would be Google Plus, as Google is gradually releasing its API methods. I also started to implement the Picasa Web Albums API, which may change since apparently Google intends to couple Picasa with Plus, so we'll see how it's going. Then I'll head on to the other APIs, and the community is welcome to help with the prioritization.
So far this forum has been a good channel for feedback, so I see no reason not to continue using it this way. Maybe I'll set up GitHub issue tracker when the project matures. I'll try to update my Twitter and blog (see both in my signature) with major progress notifications.
I can't speak for SpringSource on matters of official support. I have been talking with Craig from time to time about the architecture and roadmap, but nothing about moving it to SpringSource yet. I suppose the prerequisites would be to build a milestone and have the project properly documented (JavaDoc and Manual), which I intend to do in the coming month.
Thanks for your feedback and keep at it.