First up is Saad Hasmi on Windows Phone Daily:
Taking the iPod as an example, users who loved the device but wanted a better experience than iTunes for Windows (which lacked any compatible substitutes) eventually considered Mac as a viable option. That change in preference only grew with the success of the other iPod models, the iPhone, and the iPad. Microsoft is likely trying to do the same with their software, because as more people use their apps and services on other operating systems, users will become more entrenched in Microsoft's ecosystem. At some point when users feel they need a better overall experience with these services, they'll eventually prefer Windows and Windows Phone which would ideally have the best support for it.
So a very subtle Trojan horse then? Barb Darrow on GigaOM makes a similar argument, backed up by message board quotes:
But given the iPhone’s wild popularity and Microsoft’s attempt to build cloud services for customers across the spectrum, it makes sense for it to support (and try to co-opt?) those Apple aficionados.
James Kendrick sums it up before going into some depth:
Microsoft is releasing one iPad app after another, and hopes we don’t figure out why it is doing so
...I believe the truth is a little more obscure, that Microsoft fears that the more consumers get exposed to alternative products on other platforms, the more they will desert the company’s flagship products.
I have no insider information behind my theory, but I believe this insecurity is also behind Microsoft’s insistence in making Windows 8 both the next desktop platform and the new tablet OS. The mobile space is hot, and the more customers get exposed to the competition, the more will realize for the first time that competing alternatives have come a long way and are in fact pretty good.
Finally there's a certain Ewan Spence moonlighting over on Forbes - and I'm pitching my camp down on Microsoft and Apple being a ying and yang team against Android:
Apple and Microsoft have co-existed before, on many occasions. Microsoft Office being the obvious application suite of note, but also the iPod revolution didn’t gather significant momentum until a Windows version of iTunes was released.
If you ask me, Microsoft and Apple are happy to be the ying and yang in the tech world – with Google looking to upset both of their companies there’s a certain logic in giving each other permission to go through the firewalls to help the users get the best experience possible. It might just be a case of “the enemy of my enemy is my friend” but expect to see more co-operation between Redmond and Cupertino into 2012.
And now, over to you in the comments. What's the best theory you've seen online, or have yourself?