Sphere co-founder and CEO Tony Conrad thinks the best features are the custom range feature, which allows you to slice the search result by time segments, and the bookmarklet widget, which gives you blog posts that relate to the Web page you are reading. IceRocket has blog search by time period as does Google (buried in advanced search), but Technorati has only last in, first up.
I gave Sphere a brief test drive this morning, and it was generally speedy, under a light load so far. The interface is clean and easy to navigate. I searched for "illegal aliens," and was able to see results by time periods as well as relevance or by time posted. The index covers up to four months only at this juncture.
I searched on new Sun CEO "Jonathan Schwartz," who has been in the news lately using the custom range histogram, a neat feature that allows you to interactively modify the date range. The top result by relevance for that search (see below) was clearly not the most relevant result, however. I time shifted the custom range histogram forward and the top results were more relevant, although there was sometimes a lag as Sphere dealt with the new search parameters.
For any search engine, speed and relevance are the real measures of success. I haven't had much time to deep dive on Sphere relevance and comparison to other blog search engines, but that will become a participatory sport in the blogosphere for the next few weeks. I searched on "Web 2.0" by the last hour, and didn't get a relevant result (see below), but expanding the time range produced good results.
The Sphere it bookmarklet worked nicely, delivering blogs relevant to the story, although it took some time for it to render results on some stories. Sphere actually parses the contents of the page to figure out what it is about, and then delivers the blog search results.
Sphere also gained a $3.75 million investment from Hearst Publishing, Trident Capital and Scott Kurnit, the founder of About.com, adding the the initial $500,000 angel investment.