I don't think Apple is as close as you may think initially. Steve Jobs announced during the iPad2 keynote that devs have earned over $2b from selling their apps

I don't think Apple is as close as you may think initially. Steve Jobs announced during the iPad2 keynote that devs have earned over $2b from selling their apps on the App Store. Add to that all the artists and bands that succeed by selling their music on iTunes. Plus all the podcasters that wouldn't have been discovered if it wasn't for iTunes. Plus all the authors selling books on the iBookstore. Plus the hundreds of small and large companies making accessories, cases, adapters, covers, etc for iGadgets. Plus all the big brands like Bose creating iPod compatible hi-fi equipment. All the vehicles adding iPod dock support. Added up together, I'm not sure if it matches Microsoft's ecosystem, but Apple's is probably in the tens of billions of dollars.