Image via CrunchBaseI nearly stopped using Flickr in favour of Facebook. Why? You can tag people in Facebook. Not only is that fun but it's useful too!
It's about time but Flickr has now added a "people in pictures" feature – it's on the right by the sets. You can type in a Flickr contact and add them that way, just type in a name and add them that way or you can use an email address.
The email address is the interesting bit – I've a few ways of getting your email address; I may have it from Facebook, I may have it from a random chat or a business card.
Previously I might have never guessed your Flickr username and that would have suited you as you might have used your Flickr account for personal pictures only; friends and family sort of stuff. Flickr's "people in pictures" option rumbles you now. If I have your email address and you've used it to register on Flickr then I can find you.
There's an easy solution; make sure your photostreams are locked and private if you'd prefer them to be locked and private.