You can visit the IETF web site and download the IETF OpenPGP Working Group's RFC 4880 that defines the OpenPGP standard.
The best place to go for downloading free software that implements the OpenPGP standard is The International PGP Home Page. This site in Norway has been run by PGP activist Stale Schumacher since before PGP Inc was incorporated.
Politics of cryptography and privacy:
Technical aspects of cryptography: