I remember reading an amazing story about the arms race between hackers and (I think) TV companies. The companies would constantly release updates to break the hacks and the hackers would, within hours, have found ways around them. Eventually the companies hired a specialist who released a whole series of seemingly unrelated updates that didn't appear to do anything until the final update was sent - at which point the entire system rewrote itself, locking out the hacker entirely.
I can't remember enough details to track down the specific story, but I do remember it was a thoroughly interesting read and I'm guessing someone here might be able to recall seeing it themselves.
Here is one random link I found in reference to this: http://www.geek.com/articles/news/directtv-hands-out-smack-d...