I'd like to advertise my Jabber ID in the emails I send, and I'd like to do so in an automated way (so that, in the future, smart email clients could look up my presence, ping me via Jabber to verify that I sent a certain message, etc.). So I've started to work on defining a "Jabber-ID" email header (expect an Internet-Draft soon). I've also hacked my config for both Thunderbird (my preferred email client) and Mutt (my fallback email client) to include "Jabber-ID: firstname.lastname@example.org" in the headers of my outgoing mail. Documentation is here. Feel free to edit that page to document the config for your favorite email client.
Update: Internet-Draft submitted.
Peter Saint-Andre > Journal