Apart from the money laundering issues, it is illegel in the US for anyone within the US to bet / gamble outside of the US. A yank can't call a betting agent in the Caman Islands to place a bet on anything. With online poker though it must be hard to prove where the gambling is taking place, so they follow the money, if it turns up in Peru than they have broken the law.
Gambling in the US is a huge earner for the govt so they will do anything to keep the money there.
Edit: Started a Pokerstars acc about a month ago to
![Frown :( :(](/data/emoji/2639.png)