And this is the market share for smart phones, which is itself a subset of all cell usage (12.7% of the cell market). So Apple has 11% of 13% of all cell usage, which is the context of Ballmer's quote. He also talked about it in terms of Apple's original pricing, which certainly was far more prohibitive than current pricing.
By the way, do you happen to have a link for those market share numbers?
http://www.maclife.com/article/news/apple_responsible_about_...
Have no mistake that Nokia and others are playing catchup.
They may sell more units, but they won't make very much profit, if any.
Macs are only x% of computers, but that means nothing when comparing with Windows or Dell. Apple sells the OS and the hardware. To look at it as market share, you would need to compare it to both OS's and hardware. With hardware, the market share outlook hits more problems. Apple can get a higher margin when it sells say memory then Dell can. Market share is not indicative of much.
Iphones are (not soley) in the category of phones that people buy because they want that phone specifically. They'll switch carriers, delay purchases etc. The majority of phones are sold to consumers that will pick a phone in-store, get the cheapest one, choose flexibly from a range, etc.
That kind of leverage gets you higher margins and better deals with carriers.
Basically, you can't look at market share without looking at margins. Nokia & dell sit at 2%-4% while Apple & RIM sit at around 15% - 20%.
"I think it's an interesting direction for their product, but I'm not convinced that there's a major market there."
A lot less quotable and won't haunt you later.
"We're not making a phone." - Steve Jobs on iPhone rumors