At the moment, Adobe are making a Flash plugin for the Apple iPhone with their belief that if they make it good enough, Apple will publish it. Unfortunately for Adobe and the rest of the world, the likely hood of Flash being available on the iPhone will be very slim.
To begin with, the applications that are available to download through Apple's iPhone App Store are making millions of dollars for Apple and a little for the developers making the applications. If Flash was available on the iPhone, it would be able to avoid the whole App Store process and developers can sell their applications themselves and receive 100% of the sales.
There would be very little chance of the iPhone ever having Flash available unless there is another phone that is taking a substantial amount of the iPhone sales away, and of course this phone runs Flash. In my own point of view of the iPhone, the only 'wow' factor is the interface which has been replicated on Windows Mobile phones already.
The iPhone has a lot of restrictions and I believe it is only popular because of Apple's Marketing strategies, and the popularity they gain with younger audiences. I have an iMate JasJam which has more features then the iPhone and it's nearly 2 years old, so I'm expecting more features will be available in the latest models which puts the iPhone lower on the features list.