The Unified Logging System is mentioned a few times in the later chapters of the SharePoint 2010 Administration softcover, as well as the SharePoint 2010 Developer softcover.

But they only make references to the web interface and programmatical interface for appending the log.

I advocate the use of the ULS viewer, available for free from the MSDN.

http://code.msdn.microsoft.com/ULSViewer

Its a wonderful tool. It gives you the ability to take a correlation-id from an error, and search out its root cause.

Best of Luck.