I had to help my multiblog users who just met wordpress recently about wordpress usage. They called me again n again. And I gave up! So I thought they wont call me any more if I create a new plugin and they can send their problems from wordpress interface 🙂
Its easy to use plugin. So dont worry, everybody can use it.
After that, your users will send a ticket, and all network admins will see it and answer it from network admin interface.