This one's been kicking around in my head for a while, and maybe you can all help me understand it. With any contemporary social networking site, I can control who has access to the things I share, and I can update or change or revoke the relationships that enable that access at any time.
For example, I can share a photo on Flickr with just my friends, or a post on Vox with just my family, or display my profile on Facebook to just my contacts. And then, if somebody ceases to be my friend, I can change their status and they no longer have access to that information. It's a unliateral, technologically enforced restriction, and circumventing the restriction would be tantamount to hacking and likely to get you banned from any of these services.
So, with all of that being said, how are privacy settings on social networks different than DRM restrictions placed on media content files from companies? Is it because I'm not a corporation? Is it because the DRM technology is provided by Flickr or Facebook instead of by Apple's iTunes or Microsoft's WIndows Media? Is it because I only (theoretically) grant permissions to dozens or hundreds of people, instead of millions?
This is a genuine question, because it's something I'm not sure I know how to articulate. I can certainly identify the difference in intent, but I am not sure I can explain the difference in definition. Feel free to comment here, or post a link or reply to @anildash on Twitter and I'll collect the best explanations I get.