Basically it creates a easy way to track topics. For example, everyone who is talking about the new movie Paranormal Activity is using #paranormalactivity. This way you could search for this to follow the conversation .
MySpace “empowers its global community to experience the Internet through a social lens by integrating personal profiles, photos, videos, mobile, messaging, games, and the world’s largest music community”.
Blogs – over 20 million bloggers in 2009 http://online.wsj.com/article/SB124026415808636575.html
Personal: online diary, microblog /Twitter
Communities: Word press, Blogger, Technorati, blogoshere
Corporate: marketing, branding, collaboration
Written, photo, video, music etc
Wikis : a wiki is a website that visitors can edit using their browser. Groups can use a wiki to author documents collaboratively. An example is Wikipedia.org , the collaborative encyclopedia. www.economicsnetwork.ac.uk/handbook/web/glossary.htm