Everyone is talking about Facebook.  Well, not actually everyone is talking about it, unless everyone means privacy advocates, techno-libertarians and other geeks. But it made Time magazine , so that’s some sort of marker of broader societal awareness.

Danah Boyd is ranting,  Leo Laporte is leaving, and Venessa Miemis is concerned about monetizing our conversations.    All of them have good points, but there’s an important one they’re missing.  To illustrate it , cue the blur effects and the flashback music.

It’s 2000, and you want to share something via the Internet.  You have two options.  If you want to share something privately, you can attach it to an email (if it’s not too big).  If you want that something to be out for the world to see, you put it on a web server.  The Internet has done private and public well for a long time.

So, why does anyone use Facebook,  which Eben Moglen has described as “free web hosting and some PHP doodads and you get spying for free all the time.”   The key PHP doodad is the one that allows you, without being a programmer, to share your content with some people but not all.  That’s what all social networks are about, from a publishing standpoint — defining a group that’s  allowed to “see your stuff”.

RSS and Atom do the aggregation side (keeping track of everyone else’s stuff in one place) easily, so those who read Facebook but don’t post have never needed Facebook. If the only point of Facebook is to control who can see your stuff, to the extent that Facebook makes everything public, they undermine their very raison d’être.  If my photos are going to be public, I might as well put them on Flickr.  If my status are to public, why not have them on StatusNet or Twitter or why not blog? If Facebook doesn’t give its users good privacy controls it’s giving them nothing unique and all Facebook has left is the friction created by it being difficult to migrate away. It won’t be the first time that a company has turned the difficulty of escaping into a pile of money, but it’s hard to imagine it being a good model for the long term.