ZuckGroupsIt’s no secret that Google has struggled to make its mark in the fast-growing social networking market. (Witness Google’s string of stumbles, including Buzz, Orkut and the recently-euthanized Wave).

So you wouldn’t expect Facebook, the 800-pound gorilla of social networking, to take any cues from Google when it comes to product development.

But in the wake of Facebook’s newly-unveiled Groups feature, some are pointing to an interesting presentation this summer by Google’s Paul Adams, who focuses on user experience research and social networking.

In a presentation published by various media online, Adams explains the problem of social networking sites like Facebook, in which a person’s various real-life cliques and social circles (college buddies, co-workers, family members) are inelegantly lumped into one homogeneous group of “friends.”

He uses the example of Debbie, a swim instructor in San Diego whose ten-year-old swim students “friend” her on Facebook, and are thus able to view the photos that her friends in LA, who work in a gay bar, have posted of some of their wild nights.