Ifyouattach much attention to your friend'sfriendship, you should make more time to communicatewithhim, orcallhim at times, email him or have a gatheringonce a week.
That's not to say that your contacts need to opt-in to the search giant's social networking site to join the fun -- email invites are still available by typing your friend's address alongside your circles, or individual friends should you wish to plan an awkward inter-group soiree.