Confirmed campaigns so far...
Inez & Vinoodh - 14 - Allegri, Cesare Paciotti, Chloé, Chloé fragrance, Emanuel Ungaro, Givenchy, Gucci Jewelry, Hugo Boss Selection, Jean Paul Gaultier, Just Cavalli, Mogg (Korea), Roberto Coin, Stella McCartney, Yves Saint Laurent
Mario Testino - 12 - Burberry, D&G, (D&G Pre-Fall), Dior Christal, Donna Karan, Gianfranco Ferré, Hugo Boss Black, Hugo by Hugo Boss, Michael Kors, Salvatore Ferragamo, St. John, Stefanel, Versace
David Sims - 7 - Balenciaga, Benetton, Calvin Klein Jeans, cK Kalvin Klein, Calvin Klein Beauty, Marc O'Polo, Tse
Mert & Marcus - 7 - Cacharél Liberté fragrance, Guccy Indy Bag, Giorgio Armani, Giorgio Armani Jeans, Louis Vuitton, Miu Miu, Roberto Cavalli
Steven Meisel - 7 - Alberta Ferretti, Belstaff, Dsquared2, Lanvin, Mulberry, Prada, Pringle of Scotland
Craig McDean - 6 - Anna Molinari, Blumarine, Calvin Klein collection, Christian Dior, Gucci, Joop
Karl Lagerfeld - 6 - Chanel, Chanel Acessories, (Chanel Pre-Fall + Pre-Fall Handbags), Fendi, Fendi fragance, K by Karl Lagerfeld, Karl Lagefeld galley
Peter Lindbergh - 6 - David Yurman, Hermès, Hugo Boss Orange, Lancôme 'Trèsor' Fragrance, Moschino, Moschino C&C
Terry Richardson - 6 - Angelo Marani, Christian Lacroix, H&M <3 Roberto Cavalli, Isabel Marant, Morgan, Sisley
Mario Sorrenti - 4 - Aquascutum, Carolina Herrera, Longchamp, Y-3
Camilla Akrans - 3 - Hermès fragrance, Missoni, Shiseido
Juergen Teller - 3 - Marc Jacobs, Marc by Marc Jacobs, Marc Jacobs fragrance
Steven Klein - 3 - Dolce & Gabbana, Liberty of London, Pinko
Annie Leibovitz - 2 - Bottega Veneta, Nina Ricci
Mikael Jansson - 2 - Calvin Klein White Label, Tod's
I'm sure I've missed a bunch, but like Faith said, they have at least this many...