I like the analogy of a walled garden to describe the VLE – it is a protected space where you can feel secure, but it is not completely private. Technical staff pop up in my Bb site, or a fellow students admits to connections, often enough for me to remind students that they cannot know who is reading what they post.
Can a PLE be a thing? Can an institution add Web 2.0 apps to their LMS and say “Students here is your PLE”? This is happening. I’ll do some research and post to the course forum.