"detecting suspicious activity, identifying users, and obtaining transaction records is problematic for law enforcement." - That must deeply hurts FBI people :)
"Despite the virtual nature of Bitcoin, users value the currency for many of the same reasons people trust Federal Reserve notes: they believe they can exchange the currency for goods, services, or a national currency at a later date."
People do not trust "Federal Reserve notes" (or any other official currency) - they are forced to use it, since they must pay taxes in it.
But it is good, that at least some people realize that there is no such a thing like US dollar, only those "notes" printed by Ben Bernanke and his pals.
If one day Bitcoin gets truly popular governments will be in trouble. How to tax that beast? I wonder if there is any other solution then poll tax.