Is your site IPv6 ready?
http://ready.chair6.net/Submit a URL and have a few simple tests run to determine IPv6 readiness.
Tests for AAAA records, IPv6 connectivity, and IPv4 literals (e.g. http://127.0.0.1) in HTTP/HTTPS-retrieved content. Example URLs to try? brocade.com, he.net, ipv6.google.com, www.v6.facebook.com.
My simple little project that took more work than initially planned .. comments/suggestions, fire away.