Over the past few days, we have been investigating a technical solution to the issue of sharing Facebook User IDs (UIDs). While initial press reports greatly exaggerated the implications of sharing a UID, we take this issue seriously. Our policy is already very clear that UIDs may not be shared with ad networks and data brokers, but we recognize that some developers were inadvertently sharing this information via the HTTP Referrer header.
This proposal addresses the underlying technical issue of inadvertent sharing for applications on Facebook. We are outlining the details of this proposal early in order to solicit feedback from our developers and the greater Web community. Our intent is to quickly address this issue while minimizing the impact to developers and users.