The explosive growth of wireless communications, combined with the rapid advances in high-performance portable computing, are driving the microelectronics industry toward the development of a variety of multi-functional, low-cost, compact, mixed-signal electronic products. These new products call for novel, often revolutionary, practices in functional block integration and packaging. Some of the challenges associated with the electrical design and rapid prototyping of these systems are discussed in this paper. Examples are given of existing electromagnetic modeling methodologies and associated CAD tools that can be used today to facilitate the design of these novel packages. The paper concludes with a brief discussion of on-going research activities toward the enhancement of these modeling/simulation methodologies and the eventual establishment of an elctromagnetic CAD environment for mixed-signal system electrical design.