Well, one of my observations for the Microsoft MVP Summit was that the network team at Microsoft is still very interested in hearing about what is happening with IPv6 and if anyone has done anything with IPv6. I am not sure that Microsoft has a good road map of what needs to happen to make IPv6 a reality in North America but they are paying attention.
Microsoft has several reasons for getting IPv6 out to the consumer space as quickly as possible. IPv6 will allow Microsoft devices to do peer to peer easily and allow them to get back to the model of all hosts being available and accessible which is a desirable thing when you build an OS platform for PC's.
In addition to all this, there appears to be in the works some cool applications that will be IPv6 only that will leverage that peer to peer openness that IPv6 allows. I think the next generation of Groove would be a great starting point myself.
With Server 2008 having the same network stack as Vista and both being IPv6/IPv4 I think there is an opportunity for IPv6 services to leapfrog some of the IPv4 technologies and potentially allow IPv6 to grow more quickly then originally anticipated. Only time will tell.