It probably doesn't, but since they're using bitcoin it circumvents the way that the US government enforces things like the UIGEA - pressure on banks/payment processors to not accept this class of funds. Bovada is a site that offers both sports betting and poker to US customers, but has to do some tricky things in regards to payment processing. Full Tilt Poker was shut down and their funds seized for this reason, circumventing the payments process by claiming that players bought bogus items instead of funds on the poker site.