Reddit-esque Commenting System?

Perhaps this has already been suggested, but how about a Reddit-esque commenting system instead of the current recommend system? I don't necessarily mean the inclusion of downvotes (which many see to be unhelpful), but a system where comments rise to the top based both on how many recommendations they've received and how long said comment has been there. That way, newer comments will have more of a chance of being seen, but the best comments will still be near the top.