This "new" astrology is actually based off of a different system than conventional astrology follows.
http://www.batangastoday.com/13th-zodiac-sign-ophiuchus-not-true-according-to-expert-astrologers/8778/
http://planetwaves.net/pagetwo/2011/01/13/your-zodiac-sign-is-not-wrong/

It's sidereal astrology vs. tropical (conventional) astrology.
Your sign has NOT changed unless you go by the sidereal system.