Yeah, but this article makes no sense for another reason: hardly any of the money supply is actually made up of cold hard cash! Less than 4% according to these 2004 stats: http://www.frbsf.org/education/publications/doctor-econ/2004...
Switzerland has recently entered this previously uncharted territory. It's leading to weird problems like banks being unable to process the new rates as the programmers assumed the world would never be so insane, and pension funds planning to withdraw their funds from banks and being outright denied access to their own money. There are persistent rumours about some funds thinking about building their own bunkers and storage areas for gold and cash, as they have an obligation to protect their investors funds and the SNB is now effectively confiscating people's pensions.