Hmmm. When I looked at RSD nearly five years ago, it didn’t seem so bad. In any case, here’s a ticket and a patch to get WordPress to support autodiscovery of AtomPub endpoints.
[Here, here! And the peasants rejoiced! And the reason one (influential) person in the Atom community didn't like RSD wasn't for technical reasons, but because Dave Winer is an acquaintance, and an early supporter of RSD... and he was reviled by some members of that community. Anyway, all these years later, RSD is quietly doing its job, and should be employed for this purpose. That was kinda the point, with no preference for one API over another. Thanks Sam!]
Source: Sam Ruby

It would be helpful if “Atom” was added to the “***Well known API names”. I was tempted to use “AtomPub”, but it seems TypePad currently uses “Atom”.
I tried entering this on the form provided, but it seems to be broken.
Sam Ruby
October 16, 2007 at 10:26 am
[...] Oct 16 2007, 8:42 AM: Sam Ruby and then Daniel Berlinger [inventor of RSD] have weighed in. Sam created a patch that adds Atom to WordPress’s RSD. [...]
WLW+AtomPub, Part 1: Autodiscovery « whateverblog.
October 16, 2007 at 10:57 am
@Sam: Done… for the original and the copy I control directly. I’ve sent a request to have the other copy updated. Sorry about the form, I’ll fix it as soon as I can…
d.
Daniel
October 16, 2007 at 11:19 am