Rachel Bilson is the latest fashion-y celeb to team up with Polyvore. Bilson, the star of Karl Lagerfeld's mini-films (read: extended arty commercials) for Magnum ice cream's US launch, judged a Polyvore contest to celebrate the premiere of the films at the Tribeca Film Festival. Here she is hard at work judging the contest from her little black MacBook at home. And here's the winning set, as selected by Ms. Bilson's discerning eye:

Polyvore has always managed to wrangle an impressive assortment of fashion people to guest on their site, answer questions, and judge set contests. They recently had one of Rihanna and Willow Smith stylist's, Rob Zangardi, on the site, and next week Janie Bryant will be the site's featured "style expert." But today marks the e-commerce/collage site's biggest fashion coup: Kate Moss. The supermodel graces the cover of Bryan Ferry's latest album, making her a "Roxy Girl," as the girls who cover Ferry's albums (including Jerry Hall in '75) are known. (Ferry's group, Roxy Music, disbanded in '80s, got back together, and broke up again in the early oughts.) The challenge: To create a "Roxy Girl" set inspired by photos of Moss from the Ferry album shoot. The contest is live now and lasts for four days. Moss will choose her two favorite sets on November 8th. Winners will receive a deluxe edition album and 40 page coffee table book featuring pictures of Kate Moss signed by both Kate Moss and Bryan Ferry. So start collage-ing and get that Moss stamp of approval. We recommend sneaking in some fringe and floral.

With over six million users, Polyvore is the largest fashion community online. And lately, the names and prizes they've wrangled for their growing community of set-creating users has amped up their fashion cred. They recently teamed up with Kate Moss and Janie Bryant to cull them for style advice and ask them to judge set contests, and now, they've partnered with accessories designer Rebecca Minkoff, whose bags garner something of a cult following. But this latest partnership is much more than Minkoff simply offering style advice and judging a set contest. Users will actually have the chance to redesign a Minkoff classic--the Morning After Clutch--and the winning design will be featured on the runway come February, and will be produced and sold on rebeccaminkoff.com in March. The contest, which started today and ends November 29, asks users to create their own take on Minkoff's clutch using digital images of the leather, hooks, tassels, studs, zippers, straps, and applicants. Minkoff will personally select her top ten, and then users will vote on the finalists on Minkoff's facebook page from December 1-8 to select the winner. And if having your design selected and produced as part of Minkoff's fall collection wasn't prize enough, the winner will be flown to NYC to attend Minkoff's fall show, where the bag will debut.

For Fashion's Night Out, Yves Saint Laurent is embracing social media and pairing up with Polyvore. Polyvore-files will have access to a data feed of YSL's Edition 24 products and YSL accessories to collage with or "make sets" as they say in Polyvore lingo. YSL and Polyvore are also challenging users to create the best YSL "set" and the winner will receive a YSL bag. So start e-scrap-booking people. More notably, this is the first time we've seen Polyvore, essentially a democratically curated e-commerce site, expand and collaborate with other brands beyond their standard partnerships with e-commerce sites they feature. Polyvore is already a powerhouse online, and unique in what they offer--users can create their own sets, or magazine tear sheets, from a selection of merch drawn from numerous e-commerce sites, driving traffic and shoppers back to those sites. And for Polyvore to partner first with a brand like YSL looks very promising indeed.