Facebook the biggest social networking platform creat new question

"That social norm is just something that has evolved. We view it as our role in the system to constantly be innovating and be updating what our system is to reflect what the current social norms are," he said.

That may well be the case -- and the trend for teenagers to share naked or near-naked pictures of one another online or via mobile phones may suggest mores are changing -- but privacy campaigners believe the slope is getting too slippery.