Question: How can I bring iPhone/iPad content on a Projector?
First you need a VGA adapter for iPad and iPhone. The limitation with this connector is that it does not behave in the same way as connecting a laptop to a projector. The VGA connector from apple does only allow you to project content of certain applications (e.g. picture app, movie app, etc.). It is not possible to have synchronous view of the iPad/iPhone screen and the projector. Hence, it is not possible the demonstrate navigation or arbitrary applications on the device to the audience.
E.g. Business Objects Explorer works fine (it was considered during programming of the app).
Here's a video from CNET that will walk through the process getting DisplayOut capability. But it does require Jailbreak, but if you back up your content regularly any problems caused can be wiped clean.
Rumors: Apple itself seems to use a hardwired cable that they are not sharing.