I noticed that the Safari and Chrome browsers on my iPhone and iPad exhibit somewhat unpredictable behavior when visiting websites that have both A and AAAA records, such as sixxs.net, ipv6actnow.org, etc... At times they connect using IPv6, at other times they use IPv4. Reloading a page sometimes changes the result. Their wireless interfaces always seem to have an IPv6 address though. Visiting pure-IPv6 websites has, so far, always worked, so it's not like IPv6 connectivity is flapping; it really seems to be the browser that is sometimes preferring IPv4. I wonder if people recognize this problem. Connecting through a static tunnel via Airport Extreme; also using its caching DNS. It doesn't seem to me that it is rewriting/modifying dns records. Other devices (FreeBSD, OS X) have no trouble at all...