What I find neat is we've reached an interesting situation in human social interaction whereby we've developed an entirely new set of etiquette guidelines for social networking pages. If you think on it, it's entirely fascinating!
I'm not sure we've developed, so much as actively developing. It seems like we're rather in flux: cause from what I've seen, people seem to give the same emotional heft to friend requests as they would to actual in-person offers of friendship.
This is based on completely talking out my butt, anecdotal examples, various articles I read about facebook-related angst and my own personal feelings, but it seems like the hurt feelings people experience having their friend request ignored is on par with actually being rejected as honest-injun friends which seems interesting considering it takes way less forethought to click "add friend" and thus should make a person less vulenrable in case of rejection than it does to come up to someone you know and say "Let's be friends!" and have them walk right past without saying a word.
I wonder how this will adjust going forward: will people become more descriminating about sending out FRs or will they stop taking it so personally when they get ignored, rejected, etc?
(Once again, the above is meant entirely as armchair philosophizing on my part and isn't backed up by any research whatsoever. Please don't take offense!)