Ubiquitous Computing (UbiComp), the third generation of computing, has produced many novel computing environments that are dynamic in nature and saturated with sensors, supported by a new breed of computing devices with alternative user interfaces. Although many of these environments have been built, there is a gap between their realisation and the underlying characteristics and principles of UbiComp. Many researchers have focussed on device integration, environmental monitoring, and information availability, and have ignored the need to support user mobility and the potential of using pseudo intelligence. This paper identifies core principles and characteristics of UbiComp environments and maps these to the domain of Smart Spaces in UbiComp. Specific Smart Space examples are critically analysed to determine if they truly meet the criteria to be part of UbiComp. From this analysis a novel defintion of Smart Spaces in the context of Ubiquitous Computing is presented.