This appears to be partially implemented. I can submit records for dynamic updating that "succeed", but if they contain an ipv6 address, the address is put in an A record instead of an AAAA record. It's strange seeing ipv6 addresses stored in A records instead of AAAA records (and it obviously isn't correct). Dumping the zone file in bind format confirms that this is indeed what is happening.
I had to write my own dynamic update client in PHP to even attempt this. ddclient is worthless for ipv6 updating.
Any plans on moving forward with this? I could DEFINITELY use ipv6 dynamic DNS updating.