Perhaps not a bug as such but personally I'd prefer links, especially those that point to external content, to open in a new browser window.
Cool this is good to hear ... I like the nofollow to begin with but then being removed niceThe "option" is hard coded right now, but links lose nofollow after a number (10?) of posts, so they start off with it.
As for external links, we don't actually check what's "external" and "internal" now. Ideally, we want internal links in posts to not open a new window, so we'd have to pick up the difference for that, so a rel/class isn't an issue then.