Does OpenDNS support IPv6?

Yes!

OpenDNS provides recursive IPv6 domain resolution services at the following DNS Server IP addresses: 

2620:0:ccc::2 
2620:0:ccd::2

At this time, OpenDNS provides only recursive domain resolution for IPv6 websites. Using a global network of DNS servers, OpenDNS is the first to provide reliable and fast IPv6 DNS resolution services.

As the global Internet community adopts IPv6, OpenDNS will enable the Web content filtering and security features, including malware, Command and Control Callback and phishing protections.

All of our resolvers support IPv6, for a list of local resolver locations, click here. If you have IPv6 connectivity and want OpenDNS IPv6 DNS resolution, the current best practice is to configure OpenDNS on the internal DNS servers or computers in a network. Click the appropriate link for the OpenDNS configuration procedures.

If you make changes to your DNS settings, OpenDNS recommends that you clear the DNS cache.

Additional Resources:

OpenDNS and IPv6 
OpenDNS Delivers IPv6 Sandbox 
A Note on IPv6 from Our Founder & CEO 
Test Your IPv4 and IPv6 Connectivity

OpenDNS Umbrella Customers:

OpenDNS, the Roaming Client and IPv6