gethan - 4:00 am on Mar 18, 2012 (gmt 0)
Yes - yet another parasite site. In my opinion definitely not fair use - though they do attribute the original sites. There is a "nopin" option you can include on your page* - they claim that DMCA safe habour protects them.
I'm getting traffic - note at the moment the links to sites seem to have an extra / appended - which means they will mostly be sending traffic to your 404 pages.
* opt-out is the wrong way around - bloating my code to say that I don't want them to do something illegal.
Other info - google has 45,000,000 photos from pinterest in their image search results, and all the ones I checked are from other sites, including mine.