From a statement on their site today:
Hilton Worldwide (NYSE: HLT) has identified and taken action to eradicate unauthorized malware that targeted payment card information in some point-of-sale systems. Hilton immediately launched an investigation and has further strengthened its systems.
Hilton Worldwide worked closely with third-party forensics experts, law enforcement and payment card companies on this investigation, and determined that specific payment card information was targeted by this malware. This information includes cardholder names, payment card numbers, security codes and expiration dates, but no addresses or personal identification numbers (PINs).
Full Article