IBM has for a long time been a contributor to the Open Source community involving themselves in various projects, just take a look at http://www.ibm.com/developerworks/opensource/ Eclipse, WAS CE and many more. All this in areas where there are many competitors, Microsoft being the main competitor I would guess. Point is, all this in areas where IBM are not alone.
But, IBM has monopoly of one area, and that is the mainframe. They have full control of the whole value chain, both the hardware and the OS and then many tools as well. So here comes Hercules mainframe emulator trying to let people run mainframe applications on other hardware…and the response from IBM…lawsuit of course. I would assume mainframe being the most valuable asset IBM has control over. But I won’t try to dive into all the nifty details here, but instead just provide you with my sources, see
- Blog Foss Patents “IBM breaks the taboo and betrays its promise to the FOSS community“
- Blog Armed and Dangerous “IBM: Back to the Bad Old Days?“
- Ars Technica, Open Ended “IBM breaks OSS patent promise, targets mainframe emulator“
The last one in the list above diving a bit into the details on why IBM is making the lawsuit (apart from protecting their money). I would assume that most people understand why they do it, but that they have chosen the wrong weapon to fight against competition.