Alex at Slackerbit.ch has a new script available for Blogging by email securely with GnuPG and Movable Type:
To add some security to the script, it only posts entries that have a good GnuPG signature, and even then only if the fingerprint of the key used to sign is allowed to post. And signing emails with gpg is a snap with mutt.
By adding custom headers to the mail, you can even set the category of the entry and ping TrackBack URLs.The script takes the value of the X-MT-Category header, and if that matches the name of an existing category, this is set as the primary category for that entry.And pinging TrackBack URLs happens via the X-MT-Ping header. This header can appear multiple times, and each URL gets pinged.