@vree: Not really. If you look at the comments now, you’ll see that a 50x50 icon would fit quite perfectly next to them, either to the left or right. Even with small comments, there’s always the darker blue top line, that says the commenter’s username, and how long ago the comment was posted, and then there’s the much lighter blue area where your comment goes. Even the smallest of comments wouldn’t be made any longer by adding a small icon next to it.
Black I do think that who ever upvoted/downvoted should remain private. I can for see some petty bickering over who downvoted when when it shouldn’t be a big deal anyways