Next time there's breaking news in your neighborhood (like an earthquake) try your search on Google and on Search.Twitter.com and see which has the news faster. Twitter is instant. Google has to wait for someone to publish an article on the news and then Google needs to index that article. Plus with Google, the article's headline doesn't give you the whole story. It's a tease. You have to click over to read the story…
I don't know about an earthquake, never felt one, but in all honesty I would rather read an article the 140 characters would be a tease as much specifics couldn't be given. If you think about it twitter would be good for traffic or something like that, but only if a radio station or some larger element was relaying the message. The same goes for a natural disaster, I'm not going to go look and see about a tornado or…
For my recent experience (a comment on this page): http://news.ycombinator.com/item?id=504849