[tlrobinson]

I'm only talking about faces tagged with an actual Facebook account.

It's unlikely they would enable facial recognition for non-Facebook users. How will they know the difference between two different people tagged as "John Doe" if they're not linked to a specific account?

[sp332]

By their faces! Also gender, location, preferences, web pages visited (they still track your browser even if you don't have a profile), and by the networks of people who talk about them.