An app note (PDF!) from Xilinx on power distribution system (PDS) design using bypass/decoupling capacitors:
This application note specifies how to build power distribution systems for Virtex™ devices. It also covers the basic principles of power distribution systems and bypass or decoupling capacitors. A step-by-step process is described where a power distribution system can be designed and verified. The final section discusses additional sources of power supply noise and provides resolutions.