According to http://www.openbsd.org/57.html "IPv6 router solicitations are now sent by the kernel ("inet6 autoconf"); rtsol(8) and rtsold(8) are no longer necessary and have been removed."
Does this mean we might finally get IPv6 and DHCP support enabled by default? Currently dhcpd does not support IPv6
IPv6 is not enabled by default. It is compiled in the kernel, but interfaces don't get an IPv6 link-local address if you don't explicitely say so. When you enable IPv6, you get a link-local address, send router solicitations and process router advertisements ("IPv6 autoconfiguration"). Router advertisements carry the prefix information, and the gateway address, as well as a DNS resolver. The latter is not always processed. It does not happen on Windows 7, on Linux you need to install rdnssd and I'm fairly sure it's the same case with the various BSDs.
Sometimes, this is not enough to get global IPv6 connectivity. The router advertisement has a flag that can indicate that the host must/can request additional information through DHCPv6. While similar to DHCP, DHCPv6 is quite a different protocol; therefore you need a separate client (or you need to merge it in your DHCP implementation; much like ISC's dhclient does with the -4/-6 command line flag).
So no, OpenBSD ships with IPv6 support as well as DHCP support. it's just that IPv6 is not configured by default, and IPv6 and DHCP have little to do with each other.
Does this mean we might finally get IPv6 and DHCP support enabled by default? Currently dhcpd does not support IPv6