It almost works, and that is (as always) the interesting bit. For those interested in using commercial (free) certificates, check out the MacDevCenter article I linked to a while back. It's convoluted, but works.
As to the lucky few who actually got Mail.app working with self-signed certificates (mind you, I'm trying to get S/MIME to work, not SSL connections - those are trivial), feel free to drop me a line and save me some time. As usual, I intend to publish a comprehensive HOWTO for other folk to use - when I get it to work myself.
AppleScript Studio Tinkering
I've also started diddling with AppleScript Studio, which marks the first time I've spent more than half an hour inside Xcode. Pretty damn impressive too, and I guess I'll like it even better when I get it to work with CVS in a way I understand (the docs are more than a bit cryptic, and I've found no way to get it to work with CVS over SSH).
But right now, tell the User to go to sleep is more interesting.