It probably just means it's illegal for other sites to take your bets. As of right now, there are only a few countries which criminalize the end-user side of the equation, and prosecute players who play at an online casino. No western democracy does this. Ironically, we do not bother to block the countries that do, so you have a better chance of getting to our site from China or Saudi Arabia than you do from the States (but then again, if you get caught it's your problem).
But effectively, if you live in the US and succeed in playing on our site, you're creating more problems for us than you're creating for yourself. To the extent that we (or anyone) understands the tangle of US online gaming law, the onus is on us to do our best to keep you out. From our perspective this is a difficult, non-trivial use of our time and resources which has an incredibly harmful effect on our business - but as it's a price we've been willing to pay, we ask Americans to respectfully help us by spending their efforts trying to change their laws rather than trying to find ways to break the laws of their own country and enter our site.
Our site is entirely web based (it's a single Flash application). While there is no Android-specific deployment, we have heard of people able to play using Android tabs with the flash browser plugin. We don't expect newer Android devices to work.
By and large, if you are playing from an IP address outside the United States, then we consider the play to be coming from outside the US. Beyond our two layers of automatic blocking, we manually analyze all logins multiple times daily and have a number of criteria for manually blacklisting. We block proxies to the fullest extent possible given the nature of the internet. What players need to know is that deliberate attempts to falsify their location are considered a violation of our terms of service, and will result in suspension of their accounts - including confiscation of funds.
If we weren't using Bitcoin, none of this would be a problem. That's because no payment service that does business with online casinos is still operating legally in the US. We could rest assured that we weren't taking payments from the States because it would be the payment processor's ass on the line. The argument could be made with Bitcoin that the real payment processor is the money transmitter who people bought and sold their Bitcoins from - however, we do not feel that those processors should be held responsible for how coins are used, and we also believe that if the US gov't wanted to make a case against Bitcoin they would start with SR and the casinos. So we believe it's our responsibility to play by the rules and that we don't have the right to get other Bitcoin businesses into trouble by irresponsibly violating national laws.