There has been a lot of chatter on the CentOS list lately regarding the ups and downs of IPv6. It has not quite boiled down to a flame war yet, but now is a good time to start distilling down what everybody has had to say.
To start, what IS IPv6? Simply put, it is a newer implementation of IP addressing that allows for many more hosts, as we have been running out of IPv4 addresses and will come to the end shortly. In fact, it allows for more than 2^95 or 5x10^28 addresses per person alive on planet earth today. "Overkill!!!" you might exclaim. In the 70s, when IPv4 was designed, and there were less than 1000 hosts internetworked, you would have said the same thing about the mere 4 billion addresses allowed in that system. In an age where having your toaster internet accessible is not unheard of, you'd be surprised at how many you might use.