As a project goes through the planning and design phases, many decisions will be made. To develop with technology X instead of technology Y. To leave feature z off of the plan for this version of the release in order to hit a hard deadline. Many decisions, large and small (and sometimes the decisions about what will not be done are as important as decisions about what will be done).
How can a Project manager best capture and share the decisions that were made so that they are not continually revisited throughout the project? Should the "why" and the "who made the decision" be documented as well? How should the project manager balance the communication of key decisions without overwhelming uninterested parties with minutiae? When is it okay to revisit a decision that seemed like a good idea at the time, but does not bear out in practice?