Re: Talking of which ...
Nick Kew mentioned the GIF format, but
Nick Kew was recollecting off the top of his head. If it had been a more serious issue - for example, if it was going into a book, or if I was due to give evidence in court, I'd have given it more time and effort. In the case of GIF, it became an issue when GIF became a standard for images on the Web. It's true that wasn't an ambush, but for millions of web users putting up pages in a more innocent age, GIF was just something we used without a thought to having to licence the format.
As for SCO, that's a complicated story (even the name itself originally belonged to a different company), but the company that became SCO was itself a Linux distributor and wannabe-Redhat in the 1990s, before it fell into the hands of pirates who saw more money in extortion than in honest work.