Knowledge-based enterprises are typically conducting a large number of research and development projects simultaneously. This is a particularly challenging task in complex and diverse project landscapes. Project Portfolio Management (PPM) can be a viable framework for knowledge and innovation management in such landscapes. A standardized process with defined functions such as project data repository, project assessment, selection, reporting, and portfolio reevaluation can serve as a starting point. In this work we discuss the benefits a multidimensional evaluation framework can provide for knowledge-based enterprises. Furthermore, we describe a knowledge and learning strategy and process in the context of PPM and evaluate their practical applicability at different stages of the PPM process.