Mobile Apps: threat or menace?

I need to get down with my cell phone compadres and grok this industry. How is developing a software application for the internet network different than developing for a cellular network?

Pro: Its always with you and it knows where you are
Con: The screen is small, the network is balkanized, and the development environment is balkanized.

I'm all for a device or two for my bat belt that gives me (free) phone calls, IM/text/SMS, live TV, music, movies, live radio. I suppose its a barrier to competitors, but it seems inefficient to have to port and test my app on java/ winCE/ iPhone/ Android. Then multiply that by negotiating with the (how many thousand?) different carriers, who are greedy for ROI.

These frictions could mean that mobile apps are the technology of the future and always will be. I mean we've been able to surf the web on our cell phones for a decade, but I'll wager the numbers on this remain shockingly low. Why? Because the screen is too small. And because the greedy carriers charge too much for net access. You only get one chance to make a first impression, and nobody likes to be made to feel stupid, by a clunky UI followed later by a vague and fat net access charge.

Sometimes there's a reason there's an untapped market space. The other side of the coin can be that the ground is too hard to work.