What’s next for Pinterest: $1 billion valuation and a business model?

Image-sharing site Pinterest is reportedly close to announcing a new funding round that values it at over $1 billion. A social commerce company is also investing in the company for the first time, The Next Web says, citing an unidentified source.

According to The Next Web, the funding will be announced Friday, the same day as Facebook’s IPO.

Pinterest has raised $37.5 million in funding so far, with lead investor Andreessen Horowitz valuing the company at $200 million as of October 2011. Since then, the company, which is still invite-only, has grown quickly. It had 17.8 million monthly uniques in February 2012, according to comScore, up from 11.7 million in January 2012.