You can do this in Windows Mobile with one of the Power Tools.
It's really useful for demos. Just hook up the native device via Active Synch. , display the device screen on your PC, drive it from your PC mouse and keyboard and you can enlarge it and project it, make screen shots etc.
Beats the hell out of 10 people elbowing each other out of the way to look at the miniscule screen.
But there is no such facility on Blackberry. That sucks major league big time.
You have to do the demo. using the simulator. That leads to "smoke and mirrors" comments. And the Blackberry simulator DOESN'T simulate. It will run perfectly on the simulator and throw exceptions on the device.
My previous post concerning "blocking operation not permitted on event dispatch thread" is just one such example.