Avahi (http://avahi.org/wiki/AboutAvahi) is already installed out of the box on all recent Linux distributions, to enable IPv6 for this service make sure the /etc/avahi/avahi-daemon.conf file contains an active "use-ipv6=yes" line.
To enable m(ulticast)dns resolving of IPv6 addresses change the
"hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4"
"hosts: files mdns_minimal [NOTFOUND=return] dns mdns"
in the /etc/nsswitch.conf file
You probably have to restart nscd if used (/etc/init.d/nscd restart or service nscd restart)
Every IPv6 enabled host using Avahi/Zeroconf/Bonjour should now be pingable as hostname.local and visible using the avahi-discover utility
To add the .local domain as standard domain for dns queries you could add a "search local" to resolv.conf and the host is now pingable as just hostname.
Another useful option for users with a mixed Linux/Microsoft environment is to enable Microsoft hostname resolving by changing the line in /etc/nsswitch.conf to
"hosts: files mdns_minimal [NOTFOUND=return] dns mdns wins", just make sure to install winbind on the Linux host.