A new version of GPG that will be compatible with Snow Leopard is in development. Watch for it.

Also in the works is a new version of GPGMail that will work with Apple's Mail v4.x, the version that ships with Snow Leopard. However, GPGMail will only run when Apple Mail 4 is set (via Get Info) to run in 32 bit mode. Bleh. Apparently this is due to the age of the current code. A rewrite will be required to move it up to 64 bit compatibility and there is no schedule as to when that will happen. Bleh. But keep in mind this is Open Source freeware. Thank you to those who keep it up-to-date.

http://macgpg.sourceforge.net/

Meanwhile, PGP is NOT Snow Leopard ready either, but an update is also in the works:

http://blog.pgp.com/index.php/2009/08/sneak-peek-pgp-whole-disk-encryption-for-snow-leopard/