Fridge, a group social-networking site, was acquired by Google last night, co-founder Austin Chang tells AllThingsD.

It's an interesting move for Google+, whose signature feature is its Circles, which are managed by each person rather than as collaborative groups.

New York-based Fridge, which offered a simple and pretty group-communication tool with photo-sharing and event-planning features, had raised some curiosity when it told members last week via e-mail that it was shutting down its product. Users were told to download and save their data by July 19. (That date has now been extended to August 20.)

"Fridge will be shutting down, but the core tenets will stay on in Google+," Chang said today. He said two people from the four-member Fridge team will be moving to Mountain View, Calif., to join the Google+ team.

Groups for Google+ have actually been a part of the plan for a while, said a person familiar with Google's product development. Internally at least, groups for Google+ have been known as "shared circles."

Fridge had raised $800,000 from angel investors such as Mitch Kapor, Naval Ravikant, Keith Rabois, Jim Young, Jeremy Stoppelman, Jameson Hsu, Geoff Ralston, Jason Sander and Joshua Schachter.