But also, it may have just been an experiment that grew far beyond expectations. Some deep-secret think-tank group was playing with digital cash scenarios, perhaps as part of scenario-planning about possible futures where a cryptocurrency arises from far-left-field. Bitcoin was one of the ideas that got a lot of review and generated some vibrant internal debate: could this work? A proponent got approval to release it, under a pseudonym, to see how unaffiliated people reacted. So indirectly from a government... but not part of any master plan.
(See also my prior comment at https://news.ycombinator.com/item?id=5501803 for why I think tax collectors may be very comfortable with Bitcoin in the long run.)