Google just rolled out the first major revamp of its Blog Search site, most notably adding a Google News-style homepage. Basically, it’s yet another way to see what people are talking about across the web.

Product Manager Michael Cohen has posted a detailed explanation about how the new homepage works, but it would have been more useful to just say, “You know Google News? It’s like that, but with blogs.” Posts are divided into categories such as politics, technology and science, then all the posts on a specific topic are grouped together in clusters. So if you want to see what 98 different blogs say about Apple dropping the nondisclosure agreement for iPhone application developers, Google Blog Search is the place to do it.

I’m not sure, however, how many people will see this as a useful alternative to Google News or tech news aggregator Techmeme and its sister sites. If you compare the technology pages on Google News and Blog Search, they cover pretty much the same stories, except that the top stories in News come from sites like MSNBC and Reuters, while the top stories in Blog Search come from blogs like Late Night Wallflower and Epicenter. (The Google News tech section also includes a lot more stories about space travel, since it groups science and technology together.) And since many blogs are news sources, there are sites that show up in both News and Blog Search, such as GigaOm, VentureBeat and some of the blogs written by The New York Times reporters.

The overlap underlines the fact News and Blog Search are doing the same thing — it’s just that News does a better job of filtering. That’s not meant as a knock on any particular blog. But when I’m looking for news, I prefer to see articles from the familiar sources featured on Google News and Techmeme, rather than a flood of blogs I’ve never heard of.

I suppose there may be an audience for Blog Search’s “every blog in the world” approach to aggregation, but I’m definitely not part of it.