In an “open letter” to Facebook users posted last night, Facebook head Mark Zuckerberg took a moment to toot his own horn, noting that Facebook now has 350 million users. He then outlined some upcoming changes designed to improve privacy settings within the social networking tool, namely the demise of regional networks. According to Zuckerberg, these networks have become too large and don’t allow for the kind of privacy controls Facebook wants to provide its users. This change, he says, is part of the updated privacy controls promised back in June.

In addition, he says that Facebook will soon allow users to specify privacy levels for each piece of content – presumably every status update, photo, link, profile detail – the user shares with the site.

All in all, the removal of regional networks was almost inevitable. After all, why should someone who happens to reside in the same metro area have special privileges to your content? Yes, Facebook has been providing privacy controls that let you hide content from even your networks for a while now, but there was no breakdown for which of your networks could or couldn’t see those pictures from that crazy holiday party – so if you shared them with your work network, you were also sharing them with everyone in your regional network as well.

This change will probably make it a bit harder for you to locate people you actually do know (or met at a bar and want to silently stalk), but hopefully will pave the way for much more user-friendly and flexible privacy controls.