[eigenvector]

I think you will find US dollars (cash) accepted quite readily in Cuba.

[toyg]

Of course, but the problem is that US authorities have a problem with you giving US dollars to Cuban businesses. You can go there and spend, sure, but when you go back, somebody will (should) knock at your door. Obviously this doesn't happen to simple tourists, only to Jay-Z/Beyonce and businessmen.

[scintill76]

I think the point is that it was illegal (under US law) in many cases for Americans to spend money there (probably in any currency).