Google Blog Search beta released
Google defines blogs as sites that use RSS and other feeds, and update content on a regular basis. Google Blog Search is not a full-text search. Google says it will not crawl content that's disallowed by a Blogger. (robot.txt file)
Google Blog Search has an advanced search page that explains various commands that are available, including the link command. The link command is great for discovering who's linking to your blog or a post on your blog. But the most powerful command in my opinion is that a blog search can be saved as an RSS alert that's updated whenever new content is posted matching the query. This is a very cool feature. I will be discussing the power behind this command and show you how to us it in the next few days.
For additional information: Google Blog Search FAQ.