cisco's been toolen around with ipv6 routers/switches since before last year so their ready to deploy. I'm sure they've even made nifty little black boxes that can go from ipv6 to ipv4 at some infinate cost ;)
Most PCs support IPv6 (Windows XP & Mac OS X all have native support. Most network gear supports IPv6 (e.g. routers), but only for software-based forwarding. Hardware-based forwarding is not yet available, meaning that while you can run IPv6 in a production network, you can't run it at the same scale as you can with IPv4. In addition, most firewalls, DHCP servers, mail servers, and other support servers aren't yet IPv6 capable.
The biggest obstacle to IPv6 deployment is that they haven't figure out yet how to allow folks to connect to multiple ISPs. There are still a lot of hurdles to overcome, and of course the biggest hurdle is that nobody has figure out how to make any money with it yet.