According to a post on the Official Google Blog, the search company is "pleased to let you know that Google search is also available over IPv6."

So far, big Internet destinations that have enabled IPv6, the next generation Internet Protocol, have been far and few between. This changed two months ago, as the Internet Engineering Task Force (IETF), inventors of IPv6, prepared for a night without IPv4. Hours before the IETF was scheduled to turn off the current version of the protocol that powers the Internet, Google made its search service available under ipv6.google.com. As I noted in the article two months ago, the new IPv6 incarnation of Google's homepage is a good showcase, but links for mail and maps pointing to non-IPv6 servers. And the fact that ipv6.google.com is only accessible over IPv6 rather than over both versions of IP make hard to start using this version of the site.

In the blog post, network engineer Lorenzo Colitti and "IPv6 Evangelist" Erik Kline noted that current projections place IPv4 address space exhaustion somewhere in late 2011, and while technologies such as Network Address Translation (NAT) can offer temporary respite, they complicate the Internet's architecture, pose barriers to the development of new applications, and run contrary to network openness principles.

They even invoke the end-to-end principle, the most sacred of the IETF's sacred cows. (The principle says that you shouldn't try to do something in the middle of the network if it can only be done properly by the sender and the receiver, anyway.) "We hope it's only a matter of time before IPv6 is widely deployed. We will be doing our part."

This begs the question of when Google will add IPv6 capability to www.google.com proper, so that IPv6 users don't have to do anything special to make use of the search giant's services. Unfortunately, this may take some time. If Google sets up www.google.com with one or more IPv6 addresses, systems that have IPv6 connectivity will prefer to use IPv6 to reach Google rather than IPv4. Unfortunately, sometimes IPv6 connectivity is a good deal slower than IPv4, or it doesn't work at all.

When Vista finds itself without a local IPv6 router, it will try to generate an IPv6 address from its IPv4 address using the 6to4 mechanism. If successful, it connects to the IPv6 Internet by "tunneling" IPv6 packets in IPv4 packets. However, if these packets are filtered by a firewall, this leads to significant delays before the system realizes there is a problem and retries over IPv4. So websites that enable IPv6 for their normal front page risk unhappy users because "the site got slower."

Anyway, Rome wasn't built in a day, and a commitment to IPv6 from one of the most important web destinations is nothing to sneeze at. Who's next?