It can be quite difficult to talk about what happens on a computer screen using words alone. Thus, many writers will use screenshots to help make a point. A picture is worth a thousand words, right? Unfortunately, many of the things that happen on a computer screen are dynamic in nature and still images just don't capture that. Enter screencasting where we record what happens on a computer screen as a video file, often with audio narration. Thus, it has become standard practice to use screencasting as a way to talk about computer applications and share computer-based presentations. Running screencasting software on a mobile device is currently inadvisable because there simply isn't enough CPU power to do so.
Working around this limitation is possible and there are several approaches to consider. I've attempted to use most of them. Thus, the following is offered so that others won't have to start out at square one as I did.
There are many fine screencasting applications for desktop and laptop computers. I use ScreenFlow for all of my screencasting ($99). It requires MacOS X 10.5 or later. On Windows, you can do much the same thing using Camtasia ($299). Both of these vendors offer lots of helpful info on their web sites. ScreenFlow has a dedicated site for that called The Screening Room.
With either of these products, you can record anything that appears on screen and do a lot of fancy post-processing to zoom, pan, add text and graphic elements and so on. Thus, the challenge is to get an iPhone, iPod touch or iPad to make an appearance on your screen. Here are several ways to do that, all require a MacOS X computer:
1) If all you need to do is show how the iPhone handles a web site or web application, iPhoney is hard to beat. This application reproduces the behavior of the Safari web browser on your laptop or desktop so you can use ScreenFlow to capture all the action and go from there.
2) The iPhone simulator in the iPhone SDK will provide you with an iPad simulator as well as an iPhone simulator. The SDK is free but you have to sign up as an Apple developer (also free) at:
http://developer.apple.com/programs/ To simulate more than what Safari does, you have to have the source code for each application and be able to use the XCode compiler. Apple doesn't provide the source code for the apps it develops so that's all beyond our reach.
3) The most flexible solution is to jailbreak your iPod touch or iPhone (difficult and bound to earn frowns from Steve Jobs). Here's where to get help in doing this: http://blog.iphone-dev.org/ Once your iPod touch or iPhone is opened up in this way, you'll have an app called Cydia for installing other apps. Then go here: http://screensplitr.com/demogod/ and learn how to download and use DemoGod for your Mac and ScreenSplitr for your iDevice.
This will get you the broadest, most flexible representation of your iDevice on your screen both for capture and for live demonstration. However, you'll find that the frame rate is not high enough for really smooth and realistic action. This is most noticeable when showing video playing on an iDevice.
The other thing that you won't see fully represented is an indication of the touch gestures. I am currently thinking through how best to handle this, with a literal image such as would be available with PhoneFinger or something less obscuring but still meaningful such as animated fingerprints.
Finally, I should mention what is probably the simplest and most effective approach, use a mid to high end document camera (c. $1200) with digital output to your computer and capture that. Other than the cost, this approach has the verisimilitude required for top notch educational visualizations.
Of course you could do what Apple does and use pro hand models and videographers who really know lighting and all that stuff. It will be expensive.