In honor of Barbie's 50th birthday, and just in time for Valentine's Day, Barbie figured prominently on the runway this last week with various Barbie-inspired fashion creations by such notable contemporary designers as Calvin Klein, Donna Karan, Tommy Hilfiger, Kenneth Cole, and Diane von Furstenberg.

Barbie's 50th Birthday Celebration will move to the UK, in time for London Fashion Week, opening on February 20th.

Fashion has always been a big part of the Barbie appeal. Any little girl who loves her Barbies will tell you that choosing and changing outfits and accessories is centrally important to the Barbie experience.

Elle has a slideshow of the complete collection from the Fall 2009 Barbie ^TM Runway Show, available online. Apparently, the toughest Barbie expert in the crowd was a bit critical. Fox News quoted a seven year old girl in the audience, Louise Kern-Kensler, as saying, "Barbie wouldn't wear those dresses. Not even the gold one." Reportedly, however, the little girl and her younger sister both very much enjoyed the fashion show.

There's an entire cottage industry around creating and hand-making Barbie clothes, and a brisk collector's market around original and vintage Barbie clothing and accessories. And Barbie is definitely not just for kids—some of the dolls and accessories run into big bucks.

From Barbie's beginnings to present day, fashion has played a vital roll in how Mattel's popular line engages children's imaginations and opens whole worlds of interactive play. Barbie is defined and described more by what she wears than perhaps by any other feature.