CGNetworks.com has an article about the VFX work in Star Wars Episode III Revenge of the Sith. Some of the tools and techniques are discussed in particular for the creation of Yoda, General Grievous and the Boga, along with the creation of the environments.
VFX Supervisor John Knoll, Animation Director Rob Coleman, Technical Animation Director James Tooley, Creature Supervisor Aaron Ferguson, Creature Simulation Supervisor Juan Luis Sanchez and Digital Matte Supervisor Jonathan Harb discuss some of the specifics. Also included are some impressive stats on the project. You can read it here: