However, company internet evangelist Vint Cerf argues that Google shouldn't (and doesn't) cross a line in the sand on user anonymity.

ENGADGET: Vint Cerf: Google services need a degree of anonymity, and they deliver it

We've heard this one before: a seemingly well intentioned corporation makes promises to uphold user anonymity, but when market pressure proves too much to handle, it's left to weigh the benefits of privacy over profit.

ENGADGET: Yahoo to retain search data for 18 months, says it's in your best interest

By default, bitcoin may not offer anonymity and untraceability like our paper cash today, but it is better described as user-defined anonymity because the decision to reveal identity and usage patterns resides solely with the bitcoin user.

FORBES: Bitcoin Obliterates 'The State Theory Of Money'

It also facilitates the many other currency features that are so important to users, but not to governments, such as unrestricted person-to-person payments, user-defined anonymity and untraceability, near-immediate bearer settlement, transaction irreversibility, reliable store of value, multi-grid capable, and decentralized processing.

FORBES: Virtual Currencies and Roach Motels

Through a combination of anonymity technology and a sophisticated user-feedback system, Silk Road makes buying and selling illegal drugs as easy as buying used electronics and seemingly as safe.

FORBES: How Technology Complicates The War On Drugs: Guns And Drugs For Sale Online

One fundamental flaw, he said, is the relative anonymity provided by the Internet's system of IP addresses, which only identify a user's general location, not a specific computer.

FORBES: Made For Hacking