I think there is a jailbroken app where you can vnc into your iphone so you can see the iphone screen on your monitor.
There are several people working on this. It is my understanding that currently the touch features get disabled when you use the output mode. Even with touch disabled, this could be a great step in the right direction to getting turn by turn navigation working in cars with built in video screens or for people that just want to mirror the content of their iphone on their car screen.
Here is one of the links:
Has anyone done this yet?
There are many legit apps available from the app store for VNC.
Just search for vnc. Jailbreak is not necessary.
Edit: sorry, I read your post wrong. I was thinking of the opposite of what you said; viewing computer screen on iphone.
You will need to Jailbreak your iPhone to make this work.
Here are the instructions to get ScreenSplitr up and running (from developer website http://www.plutinosoft.com/blog/projects/screensplitr):
1. Install ScreenSplitr via Cydia
2. Start ScreenSplitr
3. Connect an AV cable
4. The app will return to the Springboard and ScreenSplitr icon should have a “On” badge.
5. The TV should show what’s on your iPhone.
To stop, simply run ScreenSplitr again.
I don't have an AV cable and have not tried any of this.
There are a few VNC trials out there that you could certainly try out. I know mochalite is one VNC application.
This seems like a cool step toward iphone/carpc speaker-phone integration. I'd love to see a button on my main roadrunner skin that simply brings up my iphone display (maybe even just the phone portion) and allows calls to be made from the car's touchscreen and routed through the cars speakers and mic (of course, with nothing more than the phone sitting in a dock - no headset crap to plug in)...