It's eye candy.
From the Pinterest.com 'About' page...
Think of Pinterest as a virtual pinboard — a place where you can create collections of things you love and "follow" collections created by people with great taste.
People use Pinterest to collect and share all sorts of things -- wedding inspiration, favorite T-shirts, DJ equipment. You name it, people are pinning it.
We know you have great taste in something. Our mission is to make Pinterest the best place for you to share your taste with the world.
I have a Pinterest Board here. You can also find my Pinterest link on the right hand side bar of my blog. Install the Pinterest button on your browser and start pinning! A Pinterest Iphone app is coming soon! Can't wait!