R&B superstar Rihanna has been tapped to star and executive produce a new fashion competition TV show in the UK, according to Sky Living HD.  The show will reportedly be hosted by Nicola Roberts, from the British girl group Girls Aloud.  The show will feature up-and-coming fashion designers in a series of challenges in which they will create designs for musicians and celebrities, with the final task being to create outfits for Rihanna for her July 8th performance at the Wireless music festival in London.