The value of the United States dollar has been declining against metals and foreign currencies for a while now, recently dropping below the Canadian dollar last month. Now it is being rejected by rappers, American expatriates and even Warren Buffet according to the UK Independent. Five years ago, the Dollar was worth about about 0.98E. Now it is worth 0.68E.
Possibly related, the Secret Service (responsible for enforcing currency crimes) and the FBI raided and seized all of the assets of Liberty Dollar, a company which produces silver, gold and copper coins and certificates for use as private currency. The federal government is alleging (pdf warning) that the currency was involved in money laundering and wire fraud.