The attached patch supports views 'feed' selector. Simply enabling it gives all views that have the feed selector an atom feed and an icon.
Downside: atom.module doesn't come with an atom icon, so it just uses the RSS icon. This could easily be fixed by providing an icon with the module.
Downside #2: There ends up being 2 'atom' feeds listed on the view; one global one for the site, and one for the feed itself. The main atom feed should probably only be added if drupal_is_front() is true but I didn't want to force that decision on you.
Upside: Atom feeds a-plenty.