Sorry, it's pretty much just a chain letter
Keeping copyright tabs on your photos in a world where everything is shared all the time can be tricky. Recently, there has been a serious uptick in concern when it comes to Facebook. People have been pasting a "legal notice" to their wall, claiming that it somehow changes how Facebook is able to use the data (which includes photos) uploaded to the service. The truth is that it's little more than a chain letter.
By now, if you're a Facebook user, you've seen the message a bunch of times. It claims that something has changed in in the terms of service for some reason and now all your info is up for grabs unless you post that message to your wall. It's partially right. By sharing info with Facebook, you're giving them certain rights to use it in various ways. I'm not a lawyer so I'm not going to get into any serious analysis here, but you can read the terms for yourself over at Facebook.
The fact of the matter is that adding this message to your wall in no way changes how Facebook can use your data. You uploaded it and you agreed to the terms, even if you didn't read them (which you almost certainly didn't).
The safest way to share your images is to share a link to your own site or include a watermark if you don't find that kind of thing reprehensible. Posting that message isn't going to help you if things get lawyery. At the same time, though, it won't hurt you. And as Buzzfeed (a company with its own, um, unique relationship with image copyrights) puts it, it can also help open up something of a public conversation about what's fair when it comes to usage.
So what's the verdict? Do you share images on Facebook? Will this stop you?