I am very interested in FinCEN's response, please let me know.

The facebook, disney dollars, etc. are ok because they are like a gift card.
It would be illegal if Disneyland let you buy your tickets in pesos or euros because that we cannot do or it undermines the USD. Most countries it is illegal to use a currency other than what is approved by the govt. (especially countries where it would be in the best interest of the citizens to use a stronger currency, like the Zimbabwe situation prior to the usd adoption)  . Its not illegal to have foreign currency, but you do have to go through an exchange before you spend it.

A compilation of legal info in regards to bitcoins and digital currencies is an absolute must for us. I think it deserves a bit more dignity than a thread though. If I can somehow find some free time I will make a pretty basic site for everyone to compile their findings. If anyone else would rather do this let me know so I dont start on it and we both work on the same thing separately.

Great Thread, this should flourish nicely!

*edit - pretty wrong in some parts ^^^ keep reading
I should have phrased this in a more speculative way, sorry.