Pinterest looks like it is going to be the next big thing to hit the internet. It has grown massively in a short amount of time and is a very effective marketing tool for e-commerce websites, providing you have good quality images.
I have recently added the “Pin-It” button to FOODO, my Australian food website. I tried to play with adding to to every page of the website but it wouldn’t work, so I had to settle adding it only to the product pages.
The page you want to add the code to is called view.phtml located within your theme at/app/design/frontend/theme/theme/template/catalog/product/.