Google Launches Their Feed/Blog Search

This has been all over the news today --- Google just launched their "blog" search engine, complete with "search feeds" and everything else we'd expect from Google, except perhaps an integrated RSS Reader.

I certainly have nothing to complain about, as my sites practically own the "rss marketing" search ... although I'm on on top for most of the other keywords I'm targeting.

But that's really not the point. There's something more interesting and perhaps somewhat funny to discuss here:

"The goal of Blog Search is to include every blog that publishes a site feed (either RSS or Atom). It is not restricted to Blogger blogs, or blogs from any other service."

Hmmm ... now, how does Google really know what's a blog and what isn't? I'm guessing there might be some algorithms that can help identify blogs, but how can they be sure?

Or, which is actually somewhat worrying, are they equating blog search with RSS feed search, as their own description might imply?

If this is search based on feeds, why not just mark it as such?

Why?

Well, simply because RSS can carry so much more content than just blog posts ...