I use Icerocket for most of my blog searches until today. I just found out (I'm a little late) that google has a blog search function in beta.
Now don't get me wrong, Icerocket has some really cool features. They have trending of topics which is kind of cool. But Googles search engine just seems better. Only time will tell at this point. Don't dump your old search tools just yet, but things have gotten really interesting.