Possible to send email to student when assignment has been graded?

This is a great idea. Gradebook could do this by implementing Drupal's trigger/actions feature. This shouldn't be too hard to do.

I've added some basic Rules support for the gradebook module. So far I have only added one event "After assignment has been graded." But with this, you can write a rule to email a student after the assignment has been graded.

I think there is much more that could be done with Rules integration, but I will open a separate task for that.

Yes, though I don't want to duplicate code when I don't have to.

I was thinking it would be good to provide the following gradebook-level options. The teacher would be able to select any of the following, provided the administrator gave teachers an appropriate permission.

1. Email students when assignment has been graded.
2. Email students when assignment has been created.
3. Email students when assignment has been modified.

For gradebook attachments,

1. Email teacher/student when an attachment has been uploa

For gradebook responses,

1. Email teacher when response has been submitted.

I expect there should also be an administrator-level setting to set defaults for all gradebooks, allowing teachers to override (again, if they have been given the appropriate Drupal permission).

This feature has now been added to 6.x-2.x-dev. It needs careful testing. I've only been able to verify that it works in a very limited setting with just a couple of users. The feature is disabled by default. Here are the snippets from the README.txt. file.

10. Email notifications when grades or assignments are posted or modified can
    be enabled at the Email Settings fieldset on the Gradebook API configuration
    screen. The subject text and the body text of the notifications can also be
    customized on this form. Notifications for grades and assignments (and those
    provided by other Gradebook submodule) can be independently enabled. Once
    enabled, students and teachers will be able to find a Gradebook Settings
    fieldset when they edit their user profile with checkboxes that will allow
    them to opt-in to receiving these emails.

...

 J. Teachers can receive email notifications whenever a response to an
       assignment is marked completed. Like the other gradebook email
       notifications, this feature must be enabled and configured at the Email
       Settings fieldset on the Gradebook API configuration screen. Also,
       teachers can control whether or not they receive email notifications
       through the Gradebook settings fieldset added to their user profile page.

Marking as fixed for now, but I expect it will need some adjustments along the way. Also, this feature should be extended to the gradebook_attachments submodule.