Louise & Ben,
Although we didn't use moodle in 1.9 we wanted this information to figure out who marked what when. I ended up hacking together the following query (please note there may be some extra stuff in there I am no SQL expert)
SELECT c.fullname AS 'Course', u.firstname AS 'Firstname', u.lastname AS 'Lastname', gh.finalgrade AS 'Recorded Grade', gi.itemname AS 'Item Name', gh.loggeduser AS 'Grade Edited by', from_unixtime(gh.timemodified, "%m/%d/%Y") AS 'Date Modified', from_unixtime(gh.timemodified, "%h:%i %p") AS 'Time Modified'
FROM mdl_user u
JOIN mdl_grade_grades_history gh ON u.id=gh.userid
LEFT JOIN mdl_grade_items gi ON gh.itemid=gi.id
JOIN mdl_course c ON gi.courseid=c.id
WHERE u.id='348' AND c.id='135'
ORDER BY c.id, gh.timemodified
This will spit out the grade history of a single student (in this case u.id='348') in a single course (in this case c.id='135') and who entered that grade. Unfortunately it reports the user id of the the teacher that changed the grade as I couldn't figure out how to make it give me their name.
Being able to run this query tells us that the information is stored in the database even if it is not readily viewable in the gradebook.
Regards,
Dan
edit - Even stranger I think the email generated to a student when an assignment is graded includes the line "Teacher-Name has provided feedback on your Assignment-Name assignment"