No offense to ComputerWorld, but Microsoft is not Apple's primary competitor in the smartphone market. It's an interesting article, but misses the main point. Microsoft won't lead the smartphone market by 2015, has long been expected to be Android.
WSJ ran an article that compared Android's growth to Apple's iOS platform... the numbers were extremely illuminating the way they were presented. I think it was north of 10 to 1 sales ratios and Android reaching total sales milestones Apple set with the iPhone in much less time. But suffice to say Apple won't be worrying about Microsoft in four years, Apple will have to worry about Android today if they want to keep their current iPhone from sliding into a niche category.
The last article I read indicated by year's end MS will have ~5%, iOS will have ~16%, and Android will have 40% of the smartphone market. By comparison, even Blackberry is expected to have 15% of the market. Those were numbers from the IDC. It's remarkable what Apple have been able to achieve, but now that Apple set the ball rolling I don't see them keeping up.