The most fun thing about the cycle is in seeing which side bows out first. When Palm was hacking its own Pre to identify itself with an Apple USB ID, Apple kept pushing updates to break the Pre's connection to iTunes, and eventually Palm gave up on pushing new updates to re-enable the connection. With the mod crew jailbreaking iOS devices, early on Apple would push incremental updates to fix jailbreaks. More recently, Apple has stopped trying so hard, and has been looking towards more permanent solutions through hardware and with major software updates. Of course, in the end, none of it tends to work.
When the mod community decides that it wants a device open, it will inevitably happen, and no matter what manufacturers do, it will usually stay that way. The BlackBerry PlayBook got its jailbreak not too long ago from Dingleberry, RIM pushed a fix, and Dingleberry dev Chris Wade has already announced the update to version 2.1 beta to crack the new fix. RIM hasn't had to play this game in the past, but now it has to decide whether its worth it to hold of a minority of users from jailbreaking their PlayBooks.
source: Chris Wade via BGR