Kevin Burton makes a very good point about search:

This is the elephant in the blog search corner that Technorati doesn't want to talk about. Most consumers just want to search. They don't think about blogs. If you're searching Google for 'Firefox' and the top result is from a blog and the second result is mozilla.org why would you not show the first result?

That's pretty much the case. If I want to search a specific blog (something I do far more often than search "the blogosphere", I use the advanced page in Google and limit the domain. When I search, I almost never think about blog results as a separate thing.