The goal of this paper is to examine innovation activities in the Vienna software industry and to get a better understanding of the nature and geography of knowledge linkages in this sector. In the literature there seems to be a growing consensus that innovation rests on both informal local knowledge linkages and formal global networks, i.e. a combination of "local buzz" and "global pipelines". Recent studies on the software sector, however, show that the importance of different types of knowledge sources, the spatial dimension of knowledge transfer and the relevance of different channels of knowledge exchange in the software industry remain poorly understood. Drawing on a firm survey and qualitative face-to-face interviews with companies we will show that in the Vienna software industry the transfer and exchange of knowledge is highly localised and strongly informal in nature, pointing to a high significance of "local buzz" and a lack of "global pipelines". This specific pattern raises the question whether the Vienna software sector is exposed to a danger of lock in. (author´s abstract) / Series: SRE - Discussion Papers