The FBI's job is only valid for US copyrights being broken. maybe if Interpol asks nicely , but they probably don't give a squat about your copyright issues and many images in Pinterest come from places where it's OK to use them so unless the complaints are specific it's not actionable really.
Even if Pinterest users ripped off Getty the terms of service probably put the entire issue of ownership and copyright squarely back on the member doing the uploading.
This is the same game Google plays with YouTube, FlickR is the same, and Twitter and Facebook probably have more abuse than any other sites put together.
Social media and copyright are a funny thing because copyright does allow for PERSONAL use, yet those laws were written before social media and personal use didn't envision that it would happen in a place where your PERSONAL USE became widely distributed.
The laws have yet to catch up with the technology and the lawyers driving Lamborghini's that service all these accounts that dance and frolic on the backs of others IP know full well that they'll make many millions before someone finally wins a solid case against one of these companies as it'll go all the way to the Supreme Court so don't hold your breath.
Technologists can change how the public perceives things much faster than the legistlation can move which is why Pinterest et al (Google) do what they do and get away with it which is why I'm suggesting we on the other side of the fence use our technological might to make a social adjustment and make some money along the way.
We have the ability to undo the way people think because the FBI stepping in, new laws, none if it will change anything until people have something in their face forcing a difference. iTune and $0.99 songs made a difference as it was cheap and trivial to access vs. risking big fines getting caught downloading. Image and movie making used to be a skill only few possessed and now everyone does it, technology brought it to the masses. Problem is nobody ever bothered, with all that imaging technology to educated the masses about who owns what, when and why, which is where I see more technology can make a quick fix and ultimately a quick buck.
You can naysay, but I'm working on a spec and will see if it survives the "elevator pitch" with some SV big dogs I know. I don't want to build it but I know people looking for something to build :)
FWIW, I'll bet Getty, Corbis and others have permanent staff assigned to sites like Pinterest just like the RIAA and MPAA do with YouTube, Torrent, etc. which is why the FBI doesn't care as YouTube and Torrent are more up their alley with the MPAA/RIAA footing the bill.