In Cloud Computing, scheduling jobs is a major and difficult issue. The main objectives of cloud services providers are the efficient use of their computing resources. Existing cloud management systems are mostly based on centralized architectures and energy management mechanisms are suffering several limitations. To address these limitations, our contribution is to design, implement, and evaluate a novel cloud management system which provides a holistic energy-efficient VM management solution by integrating advanced VM management mechanisms such as underload mitigation, VM consolidation, and power management. In this paper, we introduce a distributed task scheduling algorithm for Clouds that enables to schedule VMs cooperatively and dynamically inside a federation of clouds. We evaluated our prototype through simulations, to compare our decentralized approach with a centralized one. Our results showed that the proposed scheduler is very reactive.