I've found three ways to combine any proprietary work with GPL and other Free Software, without a need to give away any source code, even when the Free part is under the new and most rigorous GPL3 license. And thus, as far as I can tell, there's never any good technical reason to break the Open Source license, because you can do anything you want without breaking the license. It just takes a working partnership with legal and engineering staff, and a few rules.
But Katzer and SCO are different from most companies, because both seem to have convinced themselves that they have rights to a Free Software project they didn't write, and are owed a great deal of money. Fortunately, both seem to be doing equally poorly in court. Hopefully, their performance is a message to others: taking adversary action against an Open Source project is like boxing with a beehive.
Jacobsen's case against Katzer is ongoing, although this most important appeal is completed. He has not yet convinced the judge that Katzer lied on his patent application, but what if he does? There has been no criminal prosecution of anyone for lying ("perjury") on a patent application since 1974, when the patent office eliminated its enforcement department.
Contrast that to what the defendant in a suit brought by the holder of a bogus patent faces: between $3 and $5 million dollars in legal fees per case. Without the beneficent legal team that came to Jacobsen's aid, winning such a case is so expensive that it's really losing.
The current system of software patents in the United States makes it too easy for the Katzers of the world to come after others for big bucks, even when there is significant doubt regarding the validity of their own patents. The poor defendants have to spend millions just to prove that the patent being pursued against them isn't valid, bankrupting themselves in the process.
The patent holders have little prospect of punishment when they game the system. That's a system with no sign of balance. We need to restore justice to the patent system, and we also need to take a good look at the motivation for software patents, which many economists and others feel do more to hurt innovation than to promote it.
This article only touches on the highlights of this fascinating case. The full court papers are online for you to peruse.