Why should you care? Because the result of the case is that open source licenses are valid. Violate them at your peril.
The facts were not in much dispute. This was always a question of law.
Jacobsen developed the Java Model Railroad Project (JMRI), an open source system for running model trains.
Katzer took the code, stripped out the authorship, and added it to his proprietary product. This violated the Artistic License then being used for the code. (It's now under GPL V. 2 with the Classpath exception.)
Katzer tried to argue that the software was not original, then that this was a contract issue, not a copyright question. The U.S. Court of Appeals for the Federal Circuit, the nation's main court for intellectual property, disagreed.
Now there's a settlement, with Katzer not only paying $100,000 (over 18 months) but providing a means to handle future disputes outside court. You can read the whole settlement here.
In its statement on the settlement JMRI thanked hundreds of model railroaders who contributed to its legal effort and the legal team headed by Victoria Hall of Bethesda, Md. and David McGowan of UCSD.
You might to thank them, too.