Smart Pixel Arrays (SPAs) integrate two-dimensional arrays of optoelectronic devices (VCSELs and photodetectors) with state-of-the-art silicon VLSI circuits. This technology has the potential to improve the speed and density of computing and switching systems while reducing their size and power consumption. We describe a gigabit switch that integrates multiple SPAs onto an MCM and interconnects them using free-space optical interconnects. Parallel fiber optic data links are used to interface the switch to each compute node in a workstation cluster. The interdependence between electronic packaging, optical design, system architecture and circuit design is discussed.