[mcantor]

I have to call shenanigans on this. My social circle regularly has huge debates via Facebook links and wall posts; off the top of my head, I can recall discussions about birth control, existentialism, web frameworks and the impact of video games on our culture. Social networks are tools; there is no prescribed way to use them beyond the actual codebase they run on. Yes... Facebook's design affords phatic throwaway talk more easily than it does discussion, but that doesn't mean you can't use it any other way.

[MartinCron]

Exactly, I had one of the best discussions about race, class, and privilege I've ever had on Facebook.

But not all conversations need hardcore gravitas to be valuable. There's actually a lot of information in a "cool stuff" RT. It says that the person read your status, and liked it enough to share, that tells you a lot about where your tastes align, which has been a facet of friendship as long as humans have been making friends.