Social Media usually synonymous with Social Networking-sloppy speaking people!
The Daily Show - Trend Spotting: Social Networking.
Speaking of connection and isolation...
Allow you to have different strengths of relationships and to manage these more easily. Data mining has become much easier to allow visualisation of data.
Open Source app development allows users to generate the site they actually want - people will use the site more because it can do what they want to do. It also means that the devs of the owning company don't have to do all the development. Also reduces the need for main devs to devise new apps - crowd sources innovation.
How do we get people to do things on our site?
Facebook
More people on your site means you can get more money from advertising through greater exposure and ability to charge more. But just because people see our adverts does not mean they are more effective-particularly in Social Media where users are used to filtering out ads.
Encourages accuracy but also allows you to be not quite as accurate as you should.
Twitter
No necessary reciprocity - which is a good thing you don't have to feel like you need to keep up a "friendship" but can let people think what they will.
Have a habit of slipping things in to see if people like them - yet this can be not so good see the retweet feature.
Traditional media takes longer to break news because they have stricter standards to follow; they need to do more research before they can print a story.
Provides weak connections.
Tweetdeck - and other apps - allow you to order the torrents of information.