Google has registered the g.co domain name to use as its official URL shortcut. Google had been previously using the goo.gl domain as its URL shortcut, however it seems that a three letter domain was 2 letters too big.
Explaining the decision Google have said that “The shorter the URL, the easier it is to share and remember.” The firm also highlighted one of the major problems with a URL shortener, that the user does not know what the final destination domain will be.
Gary Briggs, VP of consumer marketing at Google said, "We'll only use g.co to send you to webpages that are owned by Google, and only we can create g.co shortcuts. That means you can visit a g.co shortcut confident you will always end up at a page for a Google product or service."
Briggs also said that Google will continue to use the goo.gl domain and that it will "continue to be our public URL shortener that anybody can use to shorten URLs across the web". So while g.co will be used to shorten URLs of Google services, goo.gl will be available to the public to shorten any URL.