With iPhone, they're releasing version 2 of the software. If the features they advertize will be there and working, even someone like me might consider getting it. They open it up to third-party development (so those annoying software updates that kill any modifications one made to an iPhone and render it inoperable might stop), Exchange connectivity, support for ActiveX, etc.
PC market share, maybe, but there's more involved there, namely, the enterprise. Not too many IT people would even consider a Mac for the enterprise, and that's a mindset Apple has to offer something really good to change. Consumer market, well, that's a maybe.
The usuals, whatever I post is my opinion, yaddayaddayadda. I'm still learning this, so if you listen to me, well, good luck to you :)