This is a hot topic, I know, but I just have to bite. Apparently IANA gave away the last /8 (Class A) subnet to regional registries in February, so the scramble for those last address blocks is happening right now.
The Internet Society (http://www.isoc.org) is organizing World IPv6 Day to encourage a concerted step toward making content available via IPv6.
I decided to do my part and set up an IPv6-over-IPv4 tunnel to my spiffy cloud server (on the Rackspace Cloud) and also try out a tunnel to my currently fluctuating residential Internet connection. I then proceeded to verify my configuration (networking is really fun, especially when the "route" command I expected to use to show me whether I had a mapped route for IPv6 addresses to the shiny new Internet gave way to a "-r" option to "netstat"... guess I didn't know BSD well enough).
I am happy to conclude that I can verify bi-directional IPv6 connectivity via my tunnels! I first found freenet6 but then heard that Hurricane Electric is also a good provider, and I chose to go with HE's http://www.tunnelbroker.net
OpenDNS (a personal favorite) also released a sandbox IPv6 recursive DNS service, so I tossed that one into my DNS resolver list, too, and things are looking good (but limited of course, because so many domains are not yet IPv6 enabled).
I ran into a little hitch when trying to add the quad-A (AAAA) records to my domain's DNS configuration so that I can participate in World IPv6 Day. Unfortunately, Network Solutions did not yet add IPv6 records management to their administrative interface, so I have to make the change by email (and the link is impossible to find on the site... it's listed not next to the records management but next to the nameserver management, and though the docs refer to advanced configuration all over the place, you actually have to go to the normal configuration page to get the email address and instructions).
The most surprising thing for me learning about IPv6 so far is that the address space is actually the current space squared TWICE! I guess it is trivial, being IPv4 is a 32-bit address space and IPv6 is a 128-bit space - increasing by powers of 2 because of the binary format. There are more /64 subnets than people on the planet (with as many addresses within them), whereas the IPv4 space is about 60% of the world population (and we already used it up... hm... greedy? only 1.5 billion people are online, using up 4.5 billion addresses).
What I think is a more interesting discussion is the assignment and verification of ownership of IPv6 address blocks and addresses - there is more security built into the protocol, but I am curious especially during the migration stage how all this will be accomplished.
Registered Linux User #370740 (http://counter.li.org)