This talk will first review the challenges in the design of emerging complex systems-on-a-chip (SoC) at STMicroelectronics, from the perspective of our customers' requirements. We then present an approach to effectively integrate heterogenous parallel components - H/W or S/W - into a homogeneous programming environment. This approach, supported by ST's MultiFlex multi-processing SoC environment, allows for the combination of a range of heterogeneous processing elements, supported by high-level programming models. Two programming models are supported: a distributed system object component (DSOC) message passing model, and a symmetrical multi-processing (SMP) model using shared memory.To illustrate the concepts discussed in this paper, we have applied the MultiFlex technology to the mapping of a high-level MPEG4 video encoder (VGA resolution at 30 frames per second) onto a mixed multi-processor and hardware platform.