IPv6 in Java 1.4
Inet6Address class
::  corresponds to 0.0.0.0 (unspecified) in IPv4
::1  corresponds to 127.0.0.1 (loopback) in IPv4
::ffff:w.x.y.z  IPv4-mapped address
::w.x.y.z  to tunnel IPv6 packets over IPv4 routing
For details, see:
http://java.sun.com/j2se/1.4/docs/guide/net/ipv6_guide/