Systems biology is ubiquitous: computational modeling of molecular systems and the integrative interpretation of ever larger postgenomic datasets are accepted as useful, and perhaps even necessary, components of biological research (Serrano, 2007; Westerhoff et al., 2009), being applied in a wide variety of fields (de Lorenzo, 2008; Park et al., 2008; Young et al., 2008; Yuan et al., 2008; Zhu et al., 2008; Feist et al., 2009; Zak and Aderem, 2009).But despite this broad consensus about the importance of systems biology and its general ingredients, the diversity of definitions of systems biology has become proverbial in recent years: ask two systems biologists for the definition of their discipline, and you will get three answers.