I finally have a good reason to use IPv6. In my test environments for creating classroom labs and activties, the computers are always using a different IPv4 address range than my internal network. However, with IPv6 automatically enabled in Windows Server 2008 and Windows Vista, I can still copy files directly to the virtual machines from my regular workstation.
IPv6 automatically creates a link-local address for each computer. This allows communication between computers on the same logical network without any manual configuration. This is similar to APIPA addresses in IPv4, except, link-local addresses are done in addition to any other addresses, not as a replacement.
In this setup, I can use regular UNC paths even though the computers are on different IPv4 networks. Sweet.
Also very useful for remote control.