Basically it's a search engine for weblogs and journals and so on. Rather than indexing every page on the web, it just indexes blog entries. You can find out, for instance, who's talking about Bonnie Langford (and only two out of the seven are mine...)
Alternately you can give it a URL and it will find recent posts/entries related to whatever's on that page. E.G. plug in the URL of my page for Enigma's latest album and you get tada...
Quite a useful tool, I think. :)
