Calendar dates for getting things done is of course a basic need. As we know life doesn't always go as planned! When something doesn't get done, there should be a paradigm for "slipping it" other than going in and editting a bunch of calendar items inside different thoughts. As a quick way of allowing users to manipulate these, consider a calendar view into many thoughts. Dependencies could even be drawn between these. Without dependencies, at least a view like this could make it easy to adjust dates "en masse" based on a good filter criteria