Someone recently introduced me to a new term: "knowledge trails".

Knowledge trails represent one of the ways that communities add value to any organization. Whereas phone calls, email, and face-to-face conversations happen once and can’t easily be reused – Enterprise 2.0 solutions promote and encourage reuse. Thus a knowledge trail is the conversation, files, media and anything else associated with a conversation that can allow for the knowledge created in the conversation to be reused multiple times.

A great example that we see often is as simple as taking team, departmental, or company-wide emails and transfering them into a blog instead. Instead of the communication happening one time, the message is delivered multiple times and new team members or employees can read and take part in surrounding conversations.