Google announced today the next stages of a major social software strategy. Called Google+, the latest in a suite of services unveiled includes a selective sharing service called Circles, a personalized newsfeed type service called Sparks, group chat, instant photo uploading features and more. The fundamental paradigm of facilitating privacy and selective sharing in order to foster a greater quantity and quality of sharing is reminiscent of the philosophy that helped Facebook grow fast in its early days, but is now relatively unique in the social networking world. Facebook has systematically dialed down its group sharing features as part of a shift towards a post-privacy paradigm of being public by default. Google will take a different approach and that could prove very smart. Update: See our review of the service after a few hours of using it!

Google Circles was described in-depth here at ReadWriteWeb three months ago. At that time Google denied that Circles existed and a Google PR guy at the company’s SXSW party even gave me a blistering angry lecture about how irresponsible I was to report on something so untrue. (Google PR has been in touch today and has been very gracious.)

You can see slightly awkward demo videos about the major features on the Google Blog. Wired’s Steven Levy hung out with the Google Plus team for nearly a year and provides a good in-depth look at the big-picture strategy.

Selected Google account holders will be able to begin testing the services today but Google won’t roll them out for general availability until what it calls “field tests” are completed.

Usability looks good in the demo that’s available. We’ll offer more in-depth discussion of the product after testing it.