One of the innovative features of Office Communications Server 2007 R2 (OCS 2007 R2) was the introduction of Response Groups. The OCS 2007 R2 Response Group Service provides essentially the same functionality is ACD (Automatic Call Distribution) groups have in call centers for decades. Individuals can be assigned to groups by department or skill set so that questions and issues can be efficiently routed to the appropriate people to address them.
In trying to create and implement custom tabs in Office Commmunicator Rui Silva ran into some problems. Although he appeared to follow the steps implicitly, the custom tabs were not showing up. Check out his blog post The Case of the Disappearing Tabs to find out more about the issue, the steps he took to troubleshoot it, and what the resolution is.