I don't think there are many clients which support PGP out-of-the-box. The state of S/MIME is better though; I believe many desktop email clients already suppor

I don't think there are many clients which support PGP out-of-the-box. The state of S/MIME is better though; I believe many desktop email clients already support it by default. Still, more work needs to be done. It's a bit of a catch-22: no one is signing their emails because client support isn't that good, and client support isn't improving because no one is signing emails.