Remember Glastotag? The massive (record breaking even?) photos of several hundred thousand people stitched together and put on Facebook for people to tag away. It went all over the net, and set a trend for large photo collages of people to be tagged in that way. A nice little PR stunt for the brands that could spare the time and money putting it together.
Now Facebook has put live its face recognition technology - the system tells you and your friends when you're in a photo, even before you've labelled it up. The media privacy backlash/outcry/horror has already begun with UK newspaper cover stories on the privacy concerns.
But smart PR and digital types will be looking at interesting ways to take photos of people and make them spread even further using this new face recognition. The challenge is to tread the thin line between creepy and cool.