Perfectly legitimate, and cool for everyone.
Nordstrom's has a Pinterest page! And why not. They're pinning pictures from a catalog for whom they own the rights, they are "authentic" to what they are selling, and they're displaying attractive, attainable, easy-to-find merchandise that can be repinned without losing sleep over potential copyright infringement lawsuits. You can pin a whole fantasy wardrobe, buy it, and enjoy wearing it.
That's a way better model than the current orgy of copyright infringement. Does Nordstrom's commercial presence diminish Pinterest? One might argue that it does not, since the page has, at the time the screenshot was taken, a healthy ~19,000 followers. People like it!