tr.pmnote-641932 { display: none !important; }

Update: Ooop, corrected. Fixed my live example then forgot to clean up the actual post.

Update: Another good alternative is to replace the content with something less inane. (Tweaked to leave the rep visible)

tr.pmnote-641932 td.reply-body ul { content: url(http://icanhascheezbu
+rger.wordpress.com/files/2007/10/128347333970156250nooneunderstan.jpg
+); }
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