I think what he's asking for (if I understand correctly) is a way for the plugin to check the page I'm currently on, say it's a mixergy blog post or something, and determine if that blog post has already been submitted to HN and if there are any comments about it. That would be sweet, that way I'd know right away without having to google search (site:news.ycombinator.com) for the url, and if there' already a thread I can join in the discussion quickly.