It searches specifically for articles and books, linking you to the text of the article if publically available online, or allowing you to do a library search for it or search for references to it on the web if not. It also provides links to all web sites which have cited the work.
Could become a viable replacement for lots and lots of individual bibliographic databases if it develops successfully. I guess it all depends on how much demand for it there seems to be.
Oh, and can I be the only person who just wants the two 'o's in Google to be little eyes, with a mortar board balancing above them? Perhaps they considered it and decided it was too twee?