According to Google, it’s “a web application that organizes information chronologically. Google News Timeline allows users to view news, scanned newspapers and magazines, blog posts, sports scores, and more on a zoomable, graphical timeline.”
It’s essentially a new way to organize information in Google News, supplemented by various other sources of information (blogs, wikipedia, Magazines etc). You can search, of course, and you can then sort the results by day, week, month, year or decade — useful for easily seeing how a story or event has progressed in the news.
The great thing about Google News Timeline is that it isn’t necessarily just for news. You can add your own queries (or feeds) into the mix and get a good gist of what’s happening around the web (as a whole or as a very narrow view). Head on over to Google News Timeline to give it a try.