Skype's president, Josh Silverman explained that he did not realize that their partner in China, TOM-Skype was logging and storing user's IM that were deemed offensive by the Chinese government.Canadian researchers at the University of Toronto said that the TOM-Skype was censoring and logging text chats that contain specific, sensitive keywords may be a future subject for surveillance
Silverman already addressed the security breach issue with TOM and they've already fixed the security breach and now currently addressing the wider issue of the uploading and storage of certain messages. He also assured that Skype's PC to PC calls are secured completely
Link: Skype: We didn't know about security issues | News - Security - CNET News