You sort your contacts in gmail? I honestly would never bother, really don't see the point.
I very much doubt Google are, but Facebook might be in a good position to figure this out themselves now anyway. If I'm friends with Em, Bob, Barry and Jill, and Em and Bob are friends and Barry and Jill are friends, the friendship groups are fairly obvious aren't they?
Obviously I've never seen their data so don't know, but I wouldn't be surprised that they do have the information. Just looking at 'Mutual Friends' of people I know on Facebook it seems to be fairly well defined.
Facebook goes further than the mutual friendships and takes into account all sorts of interactions like "Like"'s, comments, etc. and probably re-sharing of contents, common events, common pictures, common places... I've been told they use that to figure out what to show you in your feed, so pretty much to know whom of your FB friends you're actually interested in.
But I'd be very surprised if they don't use that in a "group" perspective as well. Which would be very interesting because groups evolve over time but you going back to clean up your lists doesn't happen very often, if ever.
From a privacy standpoint, it is a bit scary. But it's very cool from a tech/CS point-of-view.
I very much doubt Google are, but Facebook might be in a good position to figure this out themselves now anyway. If I'm friends with Em, Bob, Barry and Jill, and Em and Bob are friends and Barry and Jill are friends, the friendship groups are fairly obvious aren't they?
Obviously I've never seen their data so don't know, but I wouldn't be surprised that they do have the information. Just looking at 'Mutual Friends' of people I know on Facebook it seems to be fairly well defined.