Gary Price has a good post about the new blog search from Ask.com.
The search has also has been integrated into Bloglines. The Bloglines search has been suffering from timeouts and infrequent updates for months, so this new version is very welcome.
Ask is doing something clever with their blog search, using user behavior data from the most popular feed reader, Bloglines, in the relevance rank of the blog search results. This allows them to figure out which feeds are most popular, exclude spammy and useless blogs, and focus attention on popular posts.
Filtering out crap is particularly important in the blogosphere. As Jim Lanzone said, as of October 2005, only 37k of the supposed 20M weblogs out there had substantial interest (more than 20 subscribers) on Bloglines. Interesting blogs are fair outweighed by the uninteresting. Focusing attention on the useful and worthwhile is critical.
By the way, do not miss the advanced search on Bloglines. It allows goodies like limiting searches to only your Bloglines subscriptions. It appeared a little buggy in my usage -- oddities like the search options changing inexplicably or sticking inappropriately on future quick searches -- but it could be really nice when they get those problems ironed out.
See also Chris Sherman's review.