I understand the urge, but I think the clean, uncluttered interface trumps that. Someone in another thread noted, if a comment is cool enough that you want to "Like" it, just say so in your own comment. - Laura Norvig

You could just use small little graphics or just a color heatmap for liked comments. No clutter, and would give the option to show liked comments "+ X more comments", instead of the current scheme by posting time. - dK

Yes, but the convention for posts is to show *who* liked the post. So, where would you put the info as to *who* liked the comment? I suppose you could put a smiley to the left of the comment and when you rollover it it shows who liked the comment. For me, though, I think it's overkill. Plus, I need to get my Friendfeed on on my slower connection - appreciate the fast load time and don't want anything to slow it down. - Laura Norvig