As “Fashion 2.0″ sites continue to innovate, the social component of these style-focused sites becomes an important tool for viral growth. Weardrobe, a site focused on capturing and sharing the street style of web users, was recently acquired by Like.com And we’ve written about Polyvore, the startup lets web shoppers pull their favorite items any online store and mix and match to create personalized outfits online. Users can then share their creations on the site and can then buy the items shown. The site is seeing rapid growth, with over 6 million unique visitors per month thanks to new branding efforts and the launch of Facebook Connect.

Polyvore’s virtual styling tool allows people to mix and match products from any online store to create fashion collages, called “sets,” and collections that can then be embedded in other sites. Armed with $7 million in funding, Polyvore has recently forged partnerships with brands like Calvin Klein, Barney’s, Lancome, Zappos Marc Jacobs, and the Gap to create branded collages that the Polyvore community of users can then share and buy from. Many of these brands use Polyvore’s technology to create contests for users.The startup collects revenue in these partnerships and also sees returns from affiliate fees when users buy

And users can now share their branded “sets” via Facebook and Twitter, serving as social advertisements for designers and fashion companies. Polyvore says 30,000 sets are created daily on the site. Launched in 2007, the startup just raised $5.6 million in funding.