I use Google's Blog Search almost exclusively, and not because it's conveniently linked to from other Google sites. I just find it to be as fast, clean and full of relevant results as Google itself. Technorati, on the other hand, tends to take a loooooooong time to generate results. Then there's Icerocket; I sometimes try it out if I don't find what I'm looking for on Google Blog Search, which is rare.
Google may have a hard time chipping away at Microsoft's market share with their free web-based spreadsheet and word processor, but search is what their brand name is all about, so it's hard to go wrong with their Blog Search tool.