Does the Yahoo! "domain keys" anti-spam measure use PGP?

[Ryan Malayter]

Yahoo's idea (http://tinyurl.com/yxft) seems to be something like a
cryptographically-enhanced SPF (http://spf.pobox.com/) which would
prevent spammers even from spoofing source IPs, but I haven't seen
details anywhere. Since there's no central PKI mentioned in Yahoo's
proposal, either, I thought they might be using OpenPGP as the signing
method keys. Does anyone know?

Regards,
	Ryan