The CIM is an information model, a conceptual view of the managed environment, that attempts to unify and extend the existing instrumentation and management standards (SNMP, DMI, CMIP, etc.) using object-oriented constructs and design. WMI uses the Common Information Model (CIM) industry standard to represent systems, applications, networks, devices, and other managed components. So if you use WMI or winrm in any way, you will encounter CIM.
Wbemsolutions.com has a nice tutorial on CIM. Check it out!
Kapil Mathur [MSFT]