28 September 2005. There are plenty of blog search engines out there; I am particularly fond of Technorati.com, and I use Feedster.com, Blogdigger.com, and Blogpulse.com, among others.

But the 800-pound gorilla has just weighed in with its own search engine, so we now have Google's Blog Search tool.

It's still in beta and - as of this writing - the blog-search option does not appear on the main Google search page. But eventually word will trickle out, so it's time to give this new blog search engine the once-over.

One potentially significant limitation is that Google only indexes the content in the feed rather than the blog itself.

Note that everyone's definition of a blog is different; in Google's eyes, a site "counts" as a blog if it offers an RSS feed and is updated regularly. One potentially significant limitation is that Google only indexes the content in the feed rather than the blog itself. This means that for blogs generating snippets in their feeds, much of the full-text content isn't searchable through Google's Blog Search. It also doesn't include most news sources (so as not to overlap with Google News, of course), so keep in mind that what you see in Google Blog Search is unmediated, first-hand reporting of current events and not edited news sources, such as newspapers and broadcast media.

In any event, if it has the Google brand, it will be adopted. I'm waiting for the first time I hear "I BlogSearched him, but he isn't talking about me."

What does Google Blog Search do? It has most of the bells and whistles of Google's Web search, particularly if you click through to the "Advanced Blog Search" page. You can search for all the words (AND), the exact phrase, "at least one of the words" (OR), "without the words" (NOT), or you can limit keywords to the blog post headline.

You can also conduct a more restrictive search by looking for words in the blog's name, posts by a particular author, and - my favorite - posts written before, after or within certain dates. One of the advantages of Google's Blog Search is that the search results can be sorted by Google's relevance ranking or by date.

As with some other blog search tools, you can set up an RSS or Atom feed of search results. If, for example, you want to monitor what people are saying about nanotechnology. Run the search in Blog Search, click the "Sorted by date" link to re-sort the results (the default, which you can't change, is relevance-sorting), and then click one of the links at the bottom of the search results page. You can select either RSS or Atom, and either 10 or 100 results. Copy the resulting URL into your feed reader, and you have an electronic clipping service of the blogosphere's take on nanotechnology.

Note that you can tap into Google's blog search index in several ways. The direct approach is blogsearch.google.com but you can also go to search.blogger.com (if you have a blogger.com account).

As I mentioned at the beginning of this article, one of the biggest (and not well-surfaced) limitations of Google Blog Search is that it isn't actually searching the full text of blogs, but merely the content that appears in blog feeds. For bloggers who only include the first couple of sentences of a blog entry in a feed - particularly those bloggers who focus on commentary rather than pointers to cool Web sites - this is a serious limitation.

Another limitation, at least for now, is that the Google Blog Search index only dates back to March 2005. Google says that it is working on indexing older posts as well, and it is a fact of the blogosphere that anything more than a few months old is, well, old. In any event, check it out and see how Blog Search compares to your current favorite blog searching tool.

© 2005 Mary Ellen Bates all rights reserved.

Mary Ellen Bates is the principal of Bates Information Services, a research and consulting business based in Boulder, CO.