All logged in users do indeed have access to the Jetpack menu. That will allow them to connect to their WordPress.com account and enable the Toolbar notifications.
Rest assured, they won't be able to change your Jetpack settings.
If you do not want them to use Toolbar Notifications, you can hide the Jetpack menu with a plugin like this one:
http://wordpress.org/extend/plugins/jetpack-only-for-admins/