Responding to Danah Boyd.
There is a very big difference between our putting walls around our own space, and other people putting walls there.
When we build or buy (or rent) our own walls, we choose when they are open or closed - when the door is locked or unlocked, who we let in, whether the curtains are drawn or open, etc.
That's called a home.
When other people control the walls, they choose whether or not to open them (which is why the invasion of search engines in Friendster comes as a rude surprise), whether the door is locked or unlocked (which is why having your personal data owned by Fox is discomfiting), etc. When other people control the walls, you can't simply pack up your (digital) possessions and leave.
That's called a prison.
Of course even these generalizations are misleading.
Sometimes our own home is a trap. Sometimes we wall ourselves off from the rest of the world, keeping ourselves apart in ways that are not healthy. It's like when the emergency services can't gt through your front door to respond to 911. Or when we hide in the basement and pretend the tsunami outside is not real.
And sometimes the prison is a sanctuary. When we cannot afford walls of our own, or when we are in danger of being pursued by predators, or we need a place for a large group of us to meet in private, then we want a place with high walls and guards around the perimeter.
Walls - like most other things - are ethically neutral. Neither good nor bad.
It's what we do with them that matters, and what other people do with them to us. If the walls increase both our security and our freedom, then (all else being equal) they are good. If they reduce our security and freedom, they are not so good.
From my perspective, the best wall is one with a door, and the best door is one with a key.