According to the Pew Internet & American Life project, as of June 2008, "33% of internet users (the equivalent of 24% of all adults) say they read blogs, with 11% of internet users doing so on a typical day." This is a 6% increase since the end of 2004. With approximately 49% of all internet users making use of a search engine daily, one can easily see why it would be important to make sure that blog content is included in search results.
Several of the major internet search engines (Google, Yahoo, Ask, etc.) have created blog search tools, and one site, Technorati, got its start as a blog-specific search engine. However, having a search engine crawl your blog isn't enough to make sure that it appears in relevant searches. Savvy internet users needed to pay attention to search engine optimization tools and principles to make sure their content reaches the widest possible audience.