New possibilities have been brought about by the stunning number of genomic sequences becoming available for photosynthetic organisms. This new world of whole genome sequence data spans the phyla from photosynthetic microbes to algae to higher plants. These whole genome projects are intrinsically interesting, but also inform the variety of other molecular sequence databases including the recent 'meta-genomic' sequencing efforts that analyze entire communities of organisms. As impressive as they are, are obviously only the beginning of the effort to decipher the biological meaning encoded within them. This book aims to highlight progress in this direction. This book aims toward a genome-level understanding of the structure, function, and evolution of photosynthetic systems and the advantages accrued from the availability of phyletically diverse sets of gene sequences for the major components of the photosynthetic apparatus. While not meant to be fully comprehensive in terms of the topics covered, it does provide detailed views of specific cases and thereby illustrates important new directions that are being taken in this fast-moving field—a field that involves the integration of bioinformatics, molecular biology, physiology, and ecology.