Please enabe ipv6 mib support in ucd-snmp. This way, if the kernel has ipv6 enabled, these MIB registers can be accessed. IPv6 client support isn't there yet. This is just --enable-ipv6 in configure, but for reference .src.rpm, see http://www.netcore.fi/pekkas/linux/ipv6/ (Note: untested, but other distributions e.g. PLD do this too without problems, so...)
OK, enabled in current rawhide version. Read ya, Phil