To clarify: for desktop, I am a dot net developer for SharePoint, but for mobile the best development platform is the one where what you develop might actually be paid for by someone. The App store on iPhone/Touch is how it should be done, easy to browse and purchase from the device in seconds in a vetted environment with QA (though sometimes draconian) with a huge user population who are very used to such micro-transactions and a well documented and updated API, seems like a good option. More than anything, Apple's approach is joined up especially the universality of the App store being able to be used on touch/iPhone and the maturity of it which gives users confidence.
Its the complete opposite of the almost schizophrenic offerings from competing parties especially regarding the DRM switching. Who is going to invest heavily in music if they fully expect the music/apps provider to go bust and pull the plug on all its servers and then switch to a different model?
I'm not knocking the Zune on its software which I know was very good and a bit different, but seemed like a wasted effort when Microsoft hardly tried very hard to get it to be mass-adopted overall. No world-wide launch, patchy support for it within MS itself and a 'follower' mentality meant that generally people wouldn't have one as a gift. The name is PR whacky and some decisions like the brown model have become its lasting legacy. Why they are maintaining the brand for the future is nuts as its a toxic asset outside of the MS faithful as far as I can see.
Its very difficult to dethrone Apple because their users and branding are entrenched and so many iPods get sold on the back of recommendation and 'cool' factor. To compete with this you have to get everything right, and MS didn't do that. they are however in good company as Sony have spectacularly failed in this regard also. Whilst the pedantic IT profs and linux users might find fault with iTunes, very few users do outside of IT, simply because the DRM is unintrusive for the most part and *overall* its significant component of the iPod offering which is unmatched and frequently overlooked.
I think this clinches it for Apple in this regard.