i have to disagree. i met my best friend through a 'social networking site'. initially we met on a message board, but our ensuing friendship was the result of a social networking site. and we've never met in person. it's an incredibly deep, supportive, genuine, lasting friendship - we have seen each other at our weakest times, and been there for each other through it all. when you click with someone, you just click, and however you encountered that person has no real bearing on the depth of that friendship.
i'm sure a majority of people on these sites are only there to extend there pseudo-popularity, but it's certainly not impossible to meet amazing people and strike up extraordinary friendships.
mock it all you want, but without myspace i would never have met my best friend, and i would have missed out on something pretty goddamn special.