Blogs, along with wikis and RSS feeds form the big three new technologies from web 2.0 and enterprise 2.0 that will impact law firm knowledge management 2.0.
A blog (like this one) is just a webpage that allows you to easily publish new information, doing so in a chronological manner, with notifications of new information being added.
A blog can give a lawyer or other employees the ability to quickly capture knowledge and publish it. As a result it is available for others to find. Since the blog post is html, even a simple search engine should be able to index it and produce good results.
Blogs may be a natural migration for lawyers. Lawyers (like me) are used to writing letters and sending them out. Essentially, that is the same process as a blog.
Personally, I find this blog to be great personal knowledge management tool. I write for me. These are thoughts I want to capture for my own later use. You reading it and finding this content is just a by product. I publish a new blog post when I feel like it and categorize it in the way that makes sense to me.
I think the big use for a blog inside a law firm will be the administrators trying to make the law firm community aware of new information, policies and happenings. I have already threatened many of my firm's practice area managers with blogs. They seem to be willing guinea pigs for blogging. (Six more weeks until our enterprise 2.0 platform is released.)
The other feature of a blog that makes it a more powerful communication device is the ability of others to participate in the blog by allowing comments. The post and comment become captured elements of the collaboration and communication.