As of v1.3, Icinga has been capable of dual stack monitoring. Making good use of Icinga Wiki, Michael Friedrich offered his tips on the very simply integration of IPv6 alongside existing IPv4 addresses.
One way is by using two different macros to assign service definitions to the host eg. $HOSTADDRESS$, $HOSTADDRESS6$ and then creating separate check commands with those. Eg. check_ping for IPv4 and IPv6.
Another, more convenient way is via the check_multi plugin by Matthias Flacke. The simple 4 step process can be found under the ‘HowTos’ category of Icinga Wiki. Simply install > define command > define host> define check commands and you should end up with:
Check out the dual stack monitoring guide yourself and feel free to browse or add your own guides to Icinga Wiki.
Cheers to Michael and Matthias for their contributions!
(Added 1/7/12) NOTE: Icinga Core is equipped with configuration attributes and command macros to enable both Icinga Classic and Icinga Web to display IPv6 as well as IPv4 addresses. Dualstack monitoring is only possible with plugins that support both types of addresses as the connection layer is located outside Icinga Core.