Each user name has a small circle to the right of it. Its color indicates your relationship to that person. You can click that circle and then make that person your friend or foe. You can also see who is friends or foes with that person as well. If you look at your own user profile, you can see all the friends, foes, freaks, and fans that you have. It really is a network.

Then you can set the preferences for your journal. You can indicate who you will allow to make comments. You can only allow friends, friends and friends of friends, or just not allow foes to post, etc..

I think it is an excellent system.