It uses an API that I use quite a bit called their pubsubhubbub. Funny name but extreemly useful push tecnology with a public api.
If you open Google Realtime and do a simple search for "breaking news" you will sit there for about 20 minutes with your mouth hanging open. You want the world as it happens that is how you get it.
Does not work real well for specific DD searches where updates are days apart, but if an event is happening right now and you want updates now it is great.