internetnews.com has some good advice for businesses wanting to get into blogging. However, they committed a newbie error: they mention searching the blogosphere but don't define what it is or how to search it.
Wikipedia, as usual, has a good definition of blogosphere: the collective term encompassing all weblogs. Consider it a subset of web sites that only contains blogs. Easy enough, but how do you search it? There are search engines dedicated to indexing and searching blogs and RSS feeds. Here's some of the more popular:
Also, standard search engines index blogs like normal sites. Some, like Google, seem to give a higher preference to blogs over standard sites.