(I tried to submit this as an issue -- feature request -- but now seem not to have the ability to post new issues.)
In doing the 4.6.3 update, I lost a little hack I did on the comments.module so that the "author" information is added to the recent comments block. I always felt that the block was rather mysterious about the recent comments, what with not saying who actually made the comments. Anyway, I went ahead and re-did the little hack on the comments module from the 4.6.3 tarball. Here are the particulars:
Starting at line 170, remove:
$items[] = l($comment->subject, 'node/'. $comment->nid, NULL, NULL, 'comment-'. $comment->cid) .'<br />'. t('%time ago', array('%time' => format_interval(time() - $comment->timestamp)));
and replace it with this:
// added hack to add commenter's name to the 'recent comments' block
$result2 = db_query('SELECT name FROM {comments} WHERE cid='.$comment->cid);
$comment_user = db_fetch_object($result2);
$items[] = l($comment->subject . '', 'node/'. $comment->nid, NULL, NULL, 'comment-'. $comment->cid) .' by '. $comment_user->name . '<br />'. t('%time ago', array('%time' => format_interval(time() - $comment->timestamp)));
This will add the commenter's name as entered in the comment into the "recent comments" block.
I hope this can be incorporated into the core distribution. It seems rather unhelpful to leave out this information in the recent comments module. I'd submit this as a custom block, but I'm not adept enough at the Drupal code to manage that. For fellow php-challenged site admins, I've uploaded the patched comment.module for 4.6.3 here. Caveat emptor.