What is a Client Access License (CAL) - Microsoft products - Guide
CAL: This is about CAL (Client Access License) - I get questions from my client whether there is need for a CAL during the purchase of MS products: Application Center, BizTalk Server,Commerce Server, CMS.....
Finally i got a Matrix from MS which gives a clear cut on whether there is a need for CAL or not.
For more info : http://www.microsoft.com/resources/sam/lic_cal.mspx