It seems as though mobile computing has fully arrived.

I would like to rewrite two of our programs for mobile devices, but am a bit lost as to which platform to target.

Complicating this decision:

• I would need to learn the relevant languages and IDEs - my coding to date has been almost all web based (PHP, JS, Actionscript, etc. Some ASPX).
• Most users seem to be religious about their mobile decision, so oral conversations leave me more confused then enlightened.
• I do not yet own a smartphone - will have to buy one once I know which platform to be aiming for.
• Both of my programs are more for business users, (one is only useful for C.P.A.s).
• I am a single developer, and cannot develop for more than one platform at a time. Getting it right is important.

Based on what I've found on the web, I would've expected RIM to be a shoo-in, and the general order to be as follows:

1. RIM Blackberry - More of them than any other brand. Despite naysayers, they've had double the sales (or perhaps 5X the sales) of any other smartphone, and have continued to grow. And, they have business users.
2. Android - According to Schmidt, they have outsold everyone else except RIM (though I can't find where I read that now), and they are just getting started. According to Comscore, they are already at 8% of the market and expected to hit Shcmidt's claims within six months.
3. Nokia - The largest worldwide. If they would just make up between Maemo or Symbian, I would be far less confused.
4. iPhone - Much more competition by other apps, fewer sales to be had, and a overlord that can delay or cancel my app at any time. Is Cocoa hard to learn?
5. Windows Mobile - Word is that version 7 will not be backwards compatible and losing market share.
6. Palm WebOS - Perhaps this should go first, as it is the only one that offers tools to make my life easy as a web application developer. No competition in marketplace. But not very many users either.

However, a search on StackOverflow shows a hugely disproportionate number of iPhone questions versus Blackberry. Likewise, there are clearly more apps on iPhone, so it must be getting developer love.

What is the one platform I should develop for? Please back up your answer with the logic.