[EGreg]

Namecoin is one way. But why do you really need an authoritative registry? Think about Google's Real Names policy. Who does it benefit? If I don't want you to see my real name, why would I want you to find me by my real name? You should be able to find me only through existing connections you already have established in internet space.

If you want some authoritative distributed hash map, you can use namecoin like you said. But think about why you actually need an authoritative registry.

Hyperlinks? The document embedding the hyperlink can also embed the IP number. In fact, that's how the underlying IP routing system works. BGP isan interesting target for spoofing as of late.

At the very least, a website wishing for others to find it by its domain name should tell more than one registry, so there isn't a single point of failure. In the trade-off between consistency and having no single point of failure, you can think of the latter as failover or backup plan.