This document discusses the potential for using cloud computing technologies within grid computing infrastructures. It begins by reviewing the history and achievements of grid computing projects like EGEE, which established a successful worldwide infrastructure. However, grids are complex and have limitations in flexibility and cost that clouds could help address. Integrating clouds and virtualization could provide grids with more dynamic elasticity and reduce costs. While challenges remain around costs, security and provider lock-in, clouds may attract more resource providers and increase flexibility. Overall grids and clouds could complement each other, with clouds helping grids scale to accommodate peak usage in a more cost-effective manner.