Apple's developer restrictions
Much fuss of late over Apple's changes to its iPad/iPhone developer agreement banning use of interpreters and translators. It's claimed to be all about preserving battery life and the user experience, or Apple's control of their manifest destiny, depending on who you read.
But what if it's also a way of encouraging use of Xcode and Macs, and (inadvertently?) promotes Xcode/Objective-C development on the Mac? Mandating that iPhone developers use Xcode and Objective-C leads to encouraging Objective-C for Mac development as a side-effect. It promotes not just iPhone/iPad expertise and iPhone/iPad-specific applications, but leads developers towards creating more feature-filled Mac-specific applications - rather than poor ports from Windows or from Unix/X (my SaVi satellite visualisation software is an example of the latter. It's suckily minimal-effort crossplatform.)
Shortterm, this restriction benefits the iPhone/iPad. Longterm, this may lead to compelling Macintosh-only applications; it's been a long time since there have been many of those.
But it's still all about Apple's control of its manifest destiny; no change there.