iPhone® as Mobile Computer
The iPhone is a telephone with a bunch of other functionality aimed at serving the general public as a Personal Digital Assistant (PDA). It has some designed-in limitations that make it somewhat difficult to use as a general mobile computing platform.
Some of the applications I can think of that would be useful to a Behavior Analyst would involve collecting hand entered data and providing on-screen feedback, both of which are fairly easily done on the iPhone. But other functions that would be required are not so easily done. I'll ponder such issues here.
Printing
The iPhone apparently has no built in support for printing. It is possible to write code that will connect to a printer and send data. But doing so requires going back to the Stone Age of computing. For example, there are no printer drivers or print services on the iPhone, so it would be necessary to handle that in custom code. Custom code for what should be an OS thing is bad.
Data Transfer
If a user had been carrying the iPhone around all day running a data collection app, it would be nice to be able to go back to her/his desk, put the phone in a dock, and have the files synched automagically to the desktop. Or at the least, have the phone show up as a disk mounted on the desktop, and the user can manually drag the data to another application.
Unfortunately, the iPhone supports neither. There is at least one application that gives access to the iPhone as a file system, but it apparently uses unofficial (i.e., unsupported) calls. And there appears to be no way to transfer data via the USB connection the way that iTunes® does; more private interface that we mere mortals are not supposed to use.