How to show iPhone screen on projector?
You can download the iPhone Dev Tools and use the emulator, this is supposedly what Steve Jobs does his presentations with (I haven't corroborated that). Otherwise you will need to jailbreak and use one of the VNC apps.

I know it sounds like you do not want to jailbreak, but you could do it just for the presentation, then go back to stock IOS afterwords. No one would know you were jailbroken except for the savy.

[Update]
Forgot to add, follow this link for what to do once jailbroke:
http://www.mp3car.com/vbulletin/iphone-mobile-osx-meshing-connect-your-car-internet-cloud/128589-mirror-your-iphone-display-extneral-display.html#post1286663