Ask Blog Search launches blog search logo unveiled its blogs and feeds search offering tonight using index data captured from Bloglines subscriptions. Users can search for feeds (good for subscription suggestions) or individual posts sorted by relevance, recency, or popularity and scoped anywhere from the last hour to the first time a user added the feed to Bloglines. The new offering is most similar to Yahoo’s feed search based on the My Yahoo! feed index. blog search

Ask’s relevance search is based on the ExpertRank algorithm and a few other pieces of proprietary secret sauce. Most recent is a reverse chronological sort for the search term. Popularity search is most likely based on the number of inbound links but could also apply special weightings for URLs bookmarked, added to an Ask user’s saved history, or Bloglines subscribers. individual blog search result

Binoculars appear below each search result, displaying the current content of the entire feed on hover. You can subscribe to an RSS feed of any search result item, or subscribe to the search itself (although does not markup the page using a link alternate). You can also post to social bookmarking sites such as Digg and directly from the search result view.

Overall I like the blog search engine and its integration with other services such as feed aggregators and social bookmarking sites. It’s lacking an easy way to specify a URL and I imagine most bloggers will continue to track links to their blogs using Technorati and other search engines.

Mark Fletcher told a few media sources last spring to expect “world-class blog search” from Ask in summer 2005. A year later and it’s here.