Celebrities have become a designing powerhouse in their own right, and in 2007, more Fab faces joined the fray. Mary-Kate and Ashley added cool contemporary line Elizabeth and James; SJP launched the budget-friendly Bitten at Steve & Barry's; Gwen's little L.A.M.B. made a runway comeback; Lauren Conrad reached her dream of becoming a designer; and both Sienna Miller and Penelope Cruz teamed with their sisters to cull up some seriously sizzlin' clothes. Admittedly: some of them were hits ...