Well, they are now some way closer to doing that! They are working with a few key retailers to introduce photo Collections that allow users to “want” or “collect” products and even have a direct link to e-commerce (f-commerce if you like). Watch out for changes at Pottery Barn, Wayfair, Victoria’s Secret, Michael Kors, Neiman Marcus, Smith Optics, and Fab.com.
I couldn’t see these from Hong Kong which may mean that the Collections are targeted to the US in this testing phase.
// UPDATE //
I spoke to Facebook Hong Kong in early March 2013 and they confirmed these trials are ongoing in the US.