The service is currently operating or rolling out operations in 18 cities, including: Atlanta, Georgia; Austin, Texas; Charlotte, North Carolina; Chicago, Illinois; Denver, Colorado; San Francisco, California; Seattle, Washington; and 11 others.
Google has recently pulled Fiber out of a few other cities, including Boston, Massachusetts, and the notable case of Louisville, Kentucky, where Google will reportedly pay $4 million to the city over the next 19 months for damages resulting from a failed attempt to deploy the service.
But if you're located in one of the cities in which Google Fiber currently operates, you can enter your address to check for availability at your specific address (coverage within cities is not comprehensive), sign up for service, or get additional information on the Google Fiber website.