In the following, we will summarize the latest developments in the areas of Grid and Cloud Computing. With the aid of the EU funded project DEISA (Distributed European Infrastructure for Supercomputing Applications), we will explain design, development, and use of e-Infrastructures, and application enabling and implementation. The second part will briefly present three science applications and their results achieved on the DEISA HPC infrastructure, in the areas of Fluid Turbulence, Lattice Quantum Chromodynamics, und Multiprotein Complexes. We will also explain the implementation of the application codes on and optimization for the distributed DEISA HPC Infrastructure.