CNN’s shiny organic output ports worked themselves into a tizzy because (oh noes) Facebook “is allowing companies to feature users’ profiles pictures and names in advertisements.”
Tam sums up my first thought on the subject - “who pays?” My second one is a little more privacy-oriented. My guideline on fora on the internet is “would I say it at a table in a crowded restaurant?” Actually, it’s a little tighter than that – I don’t announce when I travel away from home until after I have returned, while I might mention such at a table of friends out for dinner. Hence, a guideline.
The deep systemic issues around maintaining true privacy stretch well beyond the internet. In the end, a sufficiently funded and motivated organization can assemble enough useful information about anyone but the most reclusive; and the effort required to do so is not linear with results. A reasonable expectation of privacy is one thing, but “two can keep a secret if one is dead.”