In what could blossom into an ecommerce opportunity, Facebook is testing a new “Mail A Postcard” feature powered by Sincerely that lets you choose one of your photos and have Facebook send it to a friend as a postcard — in real life. You can add a message that will appear on the back, and also mail friends prints of their own photos. The sender is charged a small fee, and Facebook is trying out a few different price points.

Though built as a spur-of-the-moment Hackathon project, if Facebook rolls out Mail A Postcard it could give users a new reason to upload and interact with photos, plus earn the social network a little money too.