This tutorial paper surveys the potential implications of subwavelength optical lithography for new tools and flows in the interface between layout design and manufacturability. We review control of optical process effects by optical proximity correction (OPC) and phase-shifting masks (PSM), then focus on the implications of OPC and PSM for layout synthesis and verification methodologies. Our discussion addresses the necessary changes in the designto-manufacturing flow, including infrastructure development in the mask and process communities, evolution of design methodology, and opportunities for research and development in the physical layout and verification areas of EDA.