http://www.ibtimes.com/articles/101099/20110114/13th-zodiac-sign-zodiac-change-ophiuchus-astronomy-stars-constellation-media-twitter-12-signs-kunckl.htm
my friend posted some more articles about this.
http://www.dailyhoroscope.com/horoscope-headlines/ophiuchus-the-13th-zodiac-sign
http://planetwaves.net/pagetwo/2011/01/13/your-zodiac-sign-is-not-wrong/