The controversy stems from their terms. They claim ownership of "site content," which includes the stuff users post. The problem is people post stuff from websites they don't own. So, a lot of pictures owned by websites who don't have standing arrangements with Pinterest get gobbled up in the posting process, resized, stored on Pinterest's servers, and absorbed into Pinterest's "site content." Reasonable website owners may take issue with that policy. They may love to share content through Pinterest. Perhaps many wouldn't mind their images resampled and stored on Pinterest's servers. But, the property claim may be a bit hard to swallow.
Do I think you're going to get sued for using Pinterest? Nope. But, I'm not a lawyer. This isn't legal advice. That's just my best guess.
Do I think Pinterest is going to work this out and keep growing? Yes. But, I don't have a crystal ball. I think this is a good idea and it will continue to grow.
Do I think the company and the site are going to have to change? Yes. I see many problems with a company gleaning pics from a website, resizing them, and maintaining a version of the images on their own servers. But, that's likely the best way to do what they do.
What's next? The cleanest and safest approach would be to require that people post original content. They're big enough now they could make that move. A pain, yes. But, it solves the big problem. It also gets big brands on board in a pseudopartnership manner. Wouldn't it be nice if you found a "pin on Pinterest" link on a given page and a few cool prebuilt images were available? That would beat all those sites out there that have images, but none that work well for Pinterest. After all, who is better equipped to represent their own content than the content owner?
Pinterest's next move will be interesting to watch. They won't be able to pull off an ownership grab of content posted by third parties. And, they won't be able to escape the potential avalanche of take down notices if they don't change their policy. Stay tuned.
The Site Content problem
The Site, Application, Services and Site Content are protected by copyright, trademark, and other laws of the United States and foreign countries. Except as expressly provided in these Terms, Cold Brew Labs and its licensors exclusively own all right, title and interest in and to the Site, Application, Services and Site Content, including all associated intellectual property rights. You will not remove, alter or obscure any copyright, trademark, service mark or other proprietary rights notices incorporated in or accompanying the Site, Application, Services or Site Content.
This "ownership" clause will likely change. Today, it is the root of most intellectual property concerns.