As promised in January, Google will test IPv6 on June 8. IPv6 is the new version of the Internet Protocol which allows a lot more strategy to connect to the Internet.
"Google has been supporting IPv6 since early 2008, when we first began offering search over IPv6. Since then we've brought IPv6 support to YouTube and have been helping ISPs allow Google over IPv6 by default for their users. On World IPv6 Day, we'll be taking the next big step. Together with major web companies such as Facebook and Yahoo!, we will allow IPv6 on our main websites for 24 hours. This is a crucial phase in the transition, because while IPv6 is broadly deployed in many networks, it's never been used at such a large scale before."
Google expects that less than 0.5% of the users will be unnatural by the test. There's even a page that tests your connection and detects IPv6 connectivity issues. Even if IPv6 will be enabled for 24 hours, IPv4 will continue to be accessible.