This paper uses research on business air travel to analyse the structure and functioning of clusters through a case study of the Irish software industry in Dublin. Whereas most cluster studies have focused on the importance of geographical proximity for knowledge creation within the cluster, the importance of extra-cluster networking has only recently began to receive some attention. Recent work for instance shows that particularly successful clusters are able to build and maintain a variety of “pipelines” with relevant hot-spots around the globe (Bathelt et. al., 2004). However this strand of work tends to “black box” the means whereby such pipelines are created. By using interviews with a sample of software managers and professional...