We didn't do the customization for Amazon, so you'd have to ask them to be sure. It looks like they added all their employees to a group and either the database is updated when a thread has someone from that group participate in the thread or the JSP/template walks through each thread to see if someone from that group has participated and updates the icon.
To better serve our customers we have included functionality to automatically follow up on a case after it has been idle for more than 5 days, and then auto close after an additional 3 days of inactivity. Choose No to acknowledge that this case will remain idle for longer than 5 days.
