Has MS done that? As far as I'm aware, they haven't actively protected their devices from jailbreaking. I think only time will tell whether or not they decide to go down that path.

Edit: The question was reworded to be less vague, so I'll answer here rather than deleting the previous one. Apple has actively fought jailbreaks and unlocks time and again. From explicit code to brick the baseband in the early days of the unlock (just before I left the iPhone dev team, in late 2007), to their continuing battle to re-jail iOS devices. With each release, they're making it harder and harder to take control over your own devices.

What do you want them to do? Leave security holes unpatched or maintain backward compatibility with jailbreaking code when releasing new iOS versions?

Neither. The solution is simple: don't fix non-vulnerabilities for the purpose of breaking jailbreaks/unlocks. In a number of cases, jailbreaks have been done via real vulnerabilities, e.g. browser vulns, but this is 1) due to closing "security holes" that enabled early jailbreaks, and 2) not the majority.