A key feature of collaboration in science and software development is to have a {\em log} of what and how is being done - for private use and reuse and for sharing selected parts with collaborators, which most often today are distributed geographically on an ever larger scale. Even better if this log is {\em automatic}, created on the fly while a scientist or software developer is working in a habitual way, without the need for extra efforts. The {\tt CAVES} and {\tt CODESH} projects address this problem in a novel way, building on the concepts of {\em virtual state} and {\em virtual transition} to provide an automatic persistent logbook for sessions of data analysis or software development in a collaborating group. A repository of sessions can be configured dynamically to record and make available the knowledge accumulated in the course of a scientific or software endeavor. Access can be controlled to define logbooks of private sessions and sessions shared within or between collaborating groups.