The New York Times has published a piece about how it's very difficult for users to remove themselves from Facebook: How Sticky Is Membership on Facebook? Just Try Breaking Free

Combined with the privacy issues that surfaced earlier with the Beacon system, it suggests the dark, or at least very careless, side of community building at Facebook.

One of the dangers of marketing is that it's easy to forget that the numbers we use and the individuals we market to are not separate entities. Once we start treating our customers as data pools, we risk losing their trust and our credibility.