I am contemplating writing my first blackberry app. I am fundamentally, a C/C++ programmer (not Java), can anyone provide some guidelines on the quickest route (i.e. shallowest learning curve) to writing a blackberry app?

Any resources/links would be useful.

As an aside:

In an ideal world, I would like to write once and deploy for both Blackberry and the iPhone, but since I am targetting largely business people, I guess blackberry should be my target - right?

Is it possible to write once and deploy on BOTH iphone and BB?