Android's k9mail now Supports PGP
Android's k9mail, known as K-9, is now the first e-mail client for the Android to support PGP digital signatures and encryption using Android Privacy Guard.
K-9 and APG are both available free of charge from the Android Market.
In addition to encryption support, k9mail version 3.0 has improved IMAP support, as well as other enhancements.
You can learn more about K-9 version 3.0 in the release notes.