For an engaging, thoughtful post about the role of the internet in enforcing social norms, see The Future of Reputation: Gossip, Rumor, and Privacy on the Internet.
Here's a sample:
In Nathaniel Hawthorne’s The Scarlet Letter, Hester Prynne was forced by her colonial New England village to wear a scarlet letter A to represent her sin of adultery. The Internet is bringing back the scarlet letter in digital form – an indelible record of people’s past misdeeds. One commentator to Don Park’s post about the dog poop girl said it best: “Right or wrong, the internet is a cruel historian.”