Google isn't an hardware nor a software company.
Google business is data mining through services, so it's absolutely coherent for them to give services to Apple's users also.
BlackBerry is getting extinction, that's the reason why they are offering services.
But Microsoft ? They should try to gain customers for their own hardware and software platform...
Google isn't a software company? Ok. I'm not sure I can agree with that. How they use their software is another matter. But I'm pretty sure they are a software company +.