We've made a couple of notable improvements to the technical design which bear mention.
1. Instead of mapping the outcome/content association to a course, we map it directly to an activity. We realized we were making it harder on ourselves by giving the system the flexibility to map to anything in the course. While that might be nice in theory, in actuality a user's performance will be tied to Activity Completion and Grades, concepts that are fundamental to activities but not other plugins/objects. This works out quite nicely since questions and advanced grading criteria both relate to an activity (when implemented), and we get a major bonus of identifying the content item's relevant context within a course - it's no longer Question A in Course B. It's Question A, part of the Final Exam (or Practice Exam) in Course B. The Functional Specs are currently being updated to reflect this.
2. Outcome attempts now capture additional data points for mingrade, maxgrade, and rawgrade. This isn't a major change, we are simply updating the spec to capture what we said we would to make it more useful for instructors and recommendation plugins.
You can see the specific changes made by clicking on the following link: http://docs.moodle.org/dev/index.php?title=Outcomes_Technical_Specification&action=historysubmit&diff=37983&oldid=37930