Pinterest continues to prove itself as a valuable e-commerce platform, and today it took another big step forward in the pinterest-as-purchasing medium. The social network is now sending email updates when a user’s pinned item drops in price, building off of the May release that provided users with information about pricing and availability of pinned items. There are no customization options as of yet – it’s presently just an opt-in or opt-out preference setting – but expect to see the service built out in the coming months. In combination with Pinterest’s already commerce-ready platform, the world of social purchasing continues to burgeon.