PlanetLab and Globus Toolkit are gaining widespread adoption in their respective communities. Although designed to solve different problems-PlanetLab is deploying a worldwide infrastructure testbed for experimenting with network services, while Globus is offering general, standards-based, software for running distributed applications over aggregated, shared resources-both build infrastructures that enable federated, extensible, and secure resource sharing across trust domains. Thus, it is instructive to compare their resource management solutions. To this end, we review the approaches taken in the two systems, attempt to trace back to starting assumptions the differences in these approaches, and explore scenarios where the two platforms can cooperate to the benefit of both user communities. We believe that this is a key first step to identifying pieces that could be shared by the two communities, pieces that are complementary, and how Globus and PlanetLab might ultimately evolve together.