This is a product I had a look at when at Microsoft Redmond in July "Introducing System Center Service Manager". One of the reasons it hasn't been in the front of mind was that it was in early beta at the time.
You can find detailed information here:
This public document outlines the major points:
Hopefully we should see it appear in 2008! Its a great edition to the System Center suite.
Currently its in public Beta however, but the next version (beta 2) should be somwehere early next calendar year.
Here's the high level diagram: