There are already sci-fi fiction that features a decentralised currency, although that isn't the focus of some: 'snow crash: neal stephenson', 'cryptonomicon' and 'Diamond Age' by same author. I read a little of Snow Crash and didn't take to it. Also 'Down and Out in the Magic Kingdom' by Cory Doctorow and 'The Mandibles' by Lionel Shriver.