Since Bitcoins aren't actual currency, would it be legal to start a gambling website where it's the only accepted form of payment?
I'm located in the United States.
I've done some research and didn't find any law that deals with Bitcoins in this manner.
It's a gray area.
While there is the Unlawful Internet Gambling Enforcement Act, it doesn't explicitly mention virtual currencies like Bitcoin.
The government has a history of interpreting laws, especially when it comes to law enforcement, to get what they want.
If I were making a business out of this, I would be cautious and anticipate that it will likely get regulated in the near future.
NPR had a whole episode on this: Is Online Gambling Legal If Bitcoins, Not Dollars, Are At Stake?