From the Google Fiber Team:

The question we got most often was: “how can I learn when service will be available in my neighborhood?” The best way to stay in-the-know is to point your Chrome (of course ;-) ) browser to our “Fiber in the Triangle” webpage, enter your physical address and email address, and sign up for more information. Don’t be afraid to pass around this link, as we’ll use this list to manage our communications going forward and provide updates on our progress. While you’re on our site, feel free to browse through our FAQs, or learn more about the great product we’ll have to offer. You can also head over to our Fiber Twitter, Google+ or Facebook pages and follow/like us.