Because of patent issues with VRRP and the Internet Engineering Task Force's (IETF) point of view about patented technology in standards (that is, RAND [reasonable and nondiscriminatory]), the OpenBSD community developed their own redundancy protocol, Common Address Redundancy Protocol (CARP), which was introduced in the OpenBSD 3.5 release. One positive aspect of that architecture is the tight integration with the pf firewall and pf's clustering capabilities via pfsync.
For more information about OpenBSD CARP, look at the CARP man page at http://www.openbsd.org/cgi-bin/man.cgi?query=carp&sektion=4. Notable features are ARP-based Layer 2 load-balancing capabilities, support for both IPv4 and IPv6, and hash protection for enhanced protocol security. Example setups are provided at http://www.countersiege.com/docpfsync-carp/.