@donnacha | WordSkill - I noticed we go to all the same websites, if we're ever in the same bar, I'll purchase a beverage of choice for you. AtD is already enabled for all users on WordPress.com. As for comments, I've heard several requests for this (and checking within the HTML editor as well).

I'm working on improvements to the AtD service right now, but if no one builds this kind of addon first, I'll take a stab at it with a WP.org plugin in the future.