Conversation Prism is a diagram that shows the different channels of social media beyond the usual social networks: facebook, linkedin, twitter, etc.
Social media is often defined by the most popular social networking sites: facebook, linkedin, myspace, etc. or blogs. The newest member on the block is twitter with its one line updates on friends and family. But as this conversation prism clearly illustrates social media is growing and evolving and there are many different channels to explore. It's not important to be involved in every social media channel - but it is important to understand where your customers are and how they are communicating with each other. Pick the most appropriate "conversation" for your product. Listen to your customers.
More information on the conversation prism can be found here: http://www.briansolis.com/2008/08/introducing-conversation-prism.html