I just attempted to search for the IPv6 loopback address,
::1 which is analogous to IPv4's
::1 are fruitless (top search result: Migrating domains with 1&1), while the
127.0.0.1 searches provide some useful results. Adding quotes didn't help.
Obviously searching for just ::1 or 127.0.0.1 isn't useful, but in combination with other terms it could be useful.
I don't know what, if any, support the search engine has for IPv4 addresses in general. It seems less likely to be useful as a generic search, so maybe none. I'd argue though that
::1 will be an important search term going forward.
While I'm posting, obligatory nag for IPv6 support for Stack Exchange.