Specifications that standardize major aspects of Grid computing are currently proposed that rely on Web Service technology. The Web Service community in turn is adding basic specifications to its stack to make both sets of standards work hand in hand. We sketch how the combination of these efforts enable virtualization of both, hardware and software resources. The resulting infrastructure provides the underlying plumbing for autonomic feedback loops. Specific kinds of such feedback loops may be seen as base for dynamic provisioning of applications and their infrastructures. The role of choreographies in provisioning is outlined. Finally, application structures suitable for being provisioned "on demand" are envisioned.