Service Manager 2010 is the new workflow and incident response module that's been added to the Microsoft System Center suite of management applications. Conceptually, it's a process control application with two faces: a management console for network managers to perform workflow operations, and a Web-based help desk Self Service Portal for end users.
Service Manager 2010 needs to be purchased separately, but is heavily dependent on two other Microsoft System Center modules, Operations Manager (Formerly 'MOM') and Configuration Manager. Without these two modules as input sources, Service Manager is a pretty handicapped component, which made us wonder why, as these three modules are so heavily intertwined, they're sold separately.
The upside, however, is that they work well together. They don't mandate Microsoft infrastructure exclusively, although the joining of non-Microsoft apps, operating systems, and infrastructure is no easy task.