The paper argues that the increasing criticism towards the regulative forms of planning should be considered as a direct consequence of the antagonism produced by the growing demands of new functional uses and new spatial design introduced in the urban realm by the ITC - the international telecommunications industry, new media industries, and the "knowledge economy". The production of this new urban space should satisfy to some precise statements: it has to be flexible in its physical arrangements and temporary in its goals for land-use. The growing demand asks for spaces that are free from functional limits, especially the ones prearranged and fixed over time. When this demand proposes: its own interpretations about the images of the contemporary city; its theories about how the urban space should be organised; its own idea about how the urban process should be managed; then we note that there is more than one analogy with the ruling mode of production which governs post-industrial societies - known as the 'flexible accumulation regime'. The question at the stake is to understand if the new 'flexible city design' should be considered as an instrument which allows new dynamics and creative uses of the urban space, or if it has to be considered as a regulative instrument that is called for in order that capital maintains the whole process of urbanisation coherent with its own internal logic. Or, more probably, to understand at what point cities should tread the path which is connecting these two radical alternatives.