Public key cryptography doesn't require X.509's third party trust model, but as the author of the article points out, PGP key exchange is not quite as simple as just trusting the CAs your browser vendor decided you should trust.

Telehash is taking an approach that completely sidesteps the problem of human-memorable names, though. It uses the public key fingerprint as the "network address" of a node in a DHT. The Telehash address is globally routable, like an IP address, but there is no MITM possible, because only a node with the private key generating the address (fingerprint) can communicate at all using that address.

There is still the problem that humans don't want to type in an IP address, let alone remember something unwieldy as 9ba9c175c3c26af9df5c8163ea91d4ae4eca59ba95d66deb287c89ea0c596979. But deciding whether to trust that key is distinct from verifying data is signed with the same fingerprint.

For a simpler model, if you don't want to wade into consistent hashing and DHTs, there's also IPv6 Cryptographically-Generated Addresses[1].

[1] http://en.wikipedia.org/wiki/Cryptographically_Generated_Add...