Last year, I was lucky enough to be at a presentation by Todd Lammle, of Cisco literature fame, about IPv6. We knew nothing about IPv6 going in and we came out knowing that we definitely knew nothing. IPv6 is a whole new way of network addressing and routing. It certainly takes a lot to get your head around it. Microsoft have included support for IPv6 in Vista and rumour is that it was driven by a national IPv6 deployment in China. Windows "Longhorn" will also include support.
Microsoft has released a document that gives you an introduction to this new protocol. You should give it a read if IPv6 is i your future or even if you are just curious. Microsoft also has a website set up to support this technology.
Credit: Bink