Mistress,
according the to website its part of the Ready-to-wear Fall/Winter 2008 line and won't be available until September.
http://www.chanel.com/fashion/8#8-ready-to-wear-fall-winter-2008-9-chanel-fashion-show-1,1,34
Image 34. I like it better on the Vogue cover with Noemie Lenoir and not the long skirt