As Chris Sherman at SEW puts it, Google Launches Industrial Strength Blog Search but Danny doesn't think its completely industrial strength, in his SEW Blog post Thoughts On & Poking At Google Blog Search, where he says;
Top line thoughts? It's not spam free.
Cool thing is that you can subscribe via RSS to searches, like I often do with other blog search engines and news sites. In Danny's post about, he describes lots of the new operators that can be utilized at the blog search engine. And Google's official Google Blog Search Help is live.