They probably have the facial recognition tech, but they probably dont have the Web stuff setup so people can just drag and drop their pics to a service that automatically sorts through them and stores them intelligently.

Heck, Google/FB probably wouldn't even have to ask people to upload photos they could just ask them if they can use the photos they've already uploaded. Heck, they probably wouldn't even need to ask. Heck, they are probably doing this for the FBI already and not telling anyone :-/

EDIT: Apparently you can email your photos to the FBI if anyone reading this has anything they think is useful: Boston@ic.fbi.gov