Have been using social media sites for connecting to people for the last few years. I now have a reasonable good picture of how exactly I am using these and how they are interlinked for me
Linked In – This really was the first social media site that I started using more that 5 years ago. This was before it was called social media. It was primarily a way to connect to x-colleagues, customers and business partners. Linked is for me still the primary tool for business connections, though now there is some oevrlap with Facebook. But I still try and keep business connections on LinkedIn. So here the connections are mostly people I know in Real Life or have some business connection with.
Facebook – Originally started with Orkut but then quickly moved to Facebook as most of my old school friends were there. Facebook is primarily a Tool for keeping in touch with family and friends. Again 99% connections are people I know in Real Life. This is changing in recent months as am connecting to more people via facebook who are not really friends but more business acquaintances. Orkut is completely dormant.
Twitter – I find this to be more of a random jumble of connections, some interest based, some local contacts, some celebrities or newsbots. It is definitely a convenient platform for micro-blogging and link sharing, in some senses it seems like a more traditional broadcast medium which probably explains why everyone from CNN to DM people love it so much. It gives a quick sound-bite and a call to action which is broadcast far and wide.
The popularity of twitter probably says something that even in the world of social marketing with sophisticated tracking and metrics and personalised campaigns, there is a space for simple broadcast to also thrive.
I think Facebook is trying to redefine itself from a social networking to a broadcast site. This IMHO is a mistake. There is no real need for them to integrate these. There is a place for nuance and deeper connections as well as a need to catch up on general news. They are not mutually exclusive. Having a meaningful conversation on Twitter is impossible. Facebook mediates that in a much better format.
And where does FriendFeed, Flickr or Youtube fit into all of these, I think they are also simple broadcast mediums and should be treated as such. None of them really replace socialising functions.