I'm seeing more Pinterest pages the last couple of days. One of them is outranking me (3rd search result) since yesterday for a keyword I'm following. I used to be on the 3rd position and now dropped to the 4th place. I don't remember seeing Pinterest pages on the first page of the SERPS for this keyword, thus this is new.
I am also seeing one of my competitors who set up a Pinterest account with loads of photos pinned from his own website (and of course directing visitors back to his website). He is now, for certain keywords, ranking twice within the first 10 search results: with his website and with his Pinterest page. It looks like Pinterest can be used as a new sort of spam to drive visitors to your website. The purpose of Pinterest was collecting images of things you like and not making an images-only copy of your own site to generate traffic.