This, the 4th Transactions on Computational Systems Biology volume, contains carefully selected and enhanced contributions presented at the first Converging Science conference held at the University of Trento, Italy, in December 2004. Dedicated especially to models and metaphors from biology to bioinformatics tools, the 11 papers selected for the special issue cover a wide range of bioinformatics research, such as foundations of global computing, interdisciplinarity in innovation initiatives, biodiversity, and more.