One question that arises in the difference between a blog and a wiki. The distinction between the two becomes less clear inside the enterprise.
Mark Miller at endusersharepoint.com put it beautifully when he said:
Blogs are great when one person is trying to communicate to a team or group. Think of a blog as pushing out information from a single source to anyone who is willing to listen, “one-to-many”. The listener has the ability to participate in the communication through comments, but the main direction of the message is controlled by the person writing the blog posts. . .
By the very nature of wikis, many people will be adding content and that content can be consumed by any number of readers, “many-to-many”. At first, it seems like a free-for-all, but in an intranet situation, it is extremely useful for letting content experts participate by contributing in their area of expertise. In general, someone sets the basic beginning structure of the wiki by creating a table of contents and some starter pages. From there, user generated content drives the expansion of the wiki, based upon the needs of the participating audience.
Simple test: one or two people providing content, use a blog; many people providing content, use a wiki.