This was one of the killer features of the NewsRob Android app. Swiping to the right would mark an article as read without having to open it, while swiping left would either mark it as unread (if already unread) or flag it for keeping (i.e. don’t “mark as read” when running “mark ALL as read”).
I’m liking the web interface to NewsBlur, and this is the only thing I’m really missing from the mobile app. It doesn’t seem like functions are currently mapped to swiping article names in the list view, so it’d be a huge win if we could get this functionality.