Yesterday Google officially launched Google Blog, a tool for searching blogs exclusively. See the press release: Find out what's happening with Blog Search.
Google Blog is available here (on Google) and here (on Google's blog application, Blogger). Google indexes all blogs publicly available for "pinging", not just Blogger-based blogs. You also have the option of using the search from the top bar on any Blogger blog, such as this blog currently. Give it a whirl!