I'm sure this is mostly an IMP issue. but it would be nice if the ldap kept an optional gpg/pgp public key for a user, so when you addressed a message to him, you could click on "use public key" and encrypt the message to him. then, of course, having a decrypt option for "use local private key" or "use private key as store on the e-smith server" would be nice too.
and then we can do digital sigs too!