Google has finally launched its blog search (in beta) - available at google.com/blogsearch and blogsearch.google.com, as well as search.blogger.com - becoming the first major engine to offer complete blog and feed search capabilities (and therefore directly compete with the likes of Technorati and Feedster), reports SearchEngineWatch. Although all of the major search engines have dabbled in blog and feed search, none has offered a full-blown product.

Google defines blogs as sites that use RSS and other feeds, and update content on a regular basis. However, Google Blog Search is not a full-text search, because some publishers syndicate only excerpts of their content via RSS - and Google will not crawl content that's disallowed by a publisher.

Google Blog Search has an advanced search page, and various commands are available, including the link: command to discover who's linking to a post or blog. A blog search can also be saved as an RSS alert that's updated whenever new content is posted matching the query.

Google Blog Search is available in English, Brazilian Portuguese, Dutch, French, German, Italian, Korean, Russian and Spanish, with other coming.