As of September 17, 2013, the WorldIPv6Launch.org website was reporting 12.3% of the Alexa top 1000 websites are reachable over Ipv6. This is a significant gain from last fall when this reported number was below 3%. This shows progress from the World Launch day in June of 2012.
Does this mean the internet is on the way to full adoption of IPv6? Not quite so fast. A more telling adoption number is the Google IPv6 Adoption reporting. Google monitors users connections. It reports 1.94% of users are connecting with them with IPv6. This is a six-fold increase from the 0.37% one year ago but it remains a small percentage of all Google users. This is a better indication of a general adoption for IPv6 beyond the biggest content providers.
The major bottlenecks leading to the limited connection rates are in the end points of the internet. Older devices or newer devices constructed with older technology will not support IPv6 addressing. At this point, it's not a large problem with IPv4 and IPv6 running in parallel. Going forward, this can lead to a segregation of users that cannot afford technology upgrades from those that can.
Local Internet Service Providers that have not upgraded their routing and addressing technology are a large block to connections. Regardless of whether the users have enabled IPv6 on their devices or if a web server has upgraded, they can not reach each other if there is no IPv6 channel between them. Adoption at this level varies significantly from country to country with potential geographic isolation when services start to develop without backwards compatibility to IPv4.
Beyond large websites with dedicated in-house DNS management and facilities to handle the transition from IPv4 to IPv6, the bulk of smaller websites and blogs are running through various hosting companies. The industry standard management software with most hosting companies is cPanel and cPanel does not support IPv6. This is an important project for the company and the software upgrade is in progress but it has not been released yet. If the entire channel from the user to the website is compatible with IPv6, it doesn't matter until the website itself is able to provide IPv6 addressing.
The conversion to IPv6 is underway and progress is being made across all parts of the internet. Some heavy lifting are still required to ensure information is accessible for everyone.