Not speaking directly for my employer (in any official capacity that is), but it's is *not* as easy as as just IPv6 enabling our network, enabling ipv6 on the servers, and putting up ipv6.yahoo.com. Currently, the biggest roadblock we have is loadbalancer support (or, more specificly, lack of thereof) for IPv6 (hell, we still can't even get a I don't know what load balancer you use but all the testing I've done with my F5's has worked out. Granted I'm sure I've forgotten to test some stuff along they way but it simply hasn't been an issue during the initial testing. Considering they support IPv6 gateway and IPv6 proxy modules you can generally make things work in your environment.
I would like to know when Foundry's LB's are going to support IPv6 (unless I missed an announcement they still don't). That said- your v6 support does not have to match your v4 support to at least allow you to begin testing. You could set up a single server with v6 support, test, and not worry about it affecting production. Obviously the drive and motivation is different for different companies. Personally- I just want to get it implemented sooner rather than later so I have as much time as possible to track down bugs before normal people start using it. -Don