I am currently in Korea at a Joint UK/Korean eScience workshop. One of the questions raised was that Web Services is a requisite for cloud – a precursor to the ability to move data-analysis jobs into the cloud. Similarly this rests on whether a problem can be effectively parallelised on CPUs with poor interconnects (since the networks in Cloud Providers are not the same as in a supercomputer). Unlike Grid or Clusters undertaking collaborative analysis using nodes on a cloud provider will require a more detailed understanding of the network infrastructure (and the virtual-machine distribution) of servers on the network.  This network issue should form part of the SLA when cloud services are commissioned.