Mansion.com made a discreet announcement in the FAQ/Help section of their website this week. Here's the screenshot...
"Regulations and restrictions pertaining to betting and gaming vary from country to country. It is your sole responsibility to ensure that the laws applicable to you concerning betting and gaming do not prohibit you from opening an account and wagering with MANSION.
"US Members:
"We regret to advise that we are not accepting deposit or gaming and wagering transactions from Members in the United States. However, US Members may continue to access their MANSION account for administrative functions. "