Software development is essentially cooperative work which is collaboratively performed by various roles of persons and tools. Communication among the members of a development team (e.g. conversation) and among the tools is one of the most important characteristics for this collaborative work. To make our software development environment more effective and comfortable, we should observe what communication, collaboration and cooperation are actually made in development processes and what styles are suitable for us. In this paper, several case studies and analytic results in software development are surveyed, and I discuss what kinds of tools are required to seamlessly support group work in software development.