Pinterest making money by adding tracking code to certain user pins

How does a Web site like Pinterest make money? At least one blogger has found and revealed an apparent answer.

The online pinboard lets people share their interests and other "things they love" by pinning a photo or other image onto the site. Users can then respond to that pin by commenting on it, liking it, or re-pinning it as one of their own favorites.

Sounds pretty cut and dried. But as described by blogging site LLSocial.com, if a user submits a pin that links to an e-commerce site with an affiliate program, then Pinterest tweaks that link to add tracking code for the affiliate, according to the report. If someone clicks on the image and actually buys something from the affiliate, Pinterest gets a cut of the sales, LLSocial.com said.

Adding tracking code to links isn't by itself a cause for concern. A lot of sites do that. What seems to bother the LLSocial blogger instead is the fact that Pinterest hasn't disclosed this bit of information to its users.