We recently got a tip over to this It's Just Poison post about Veency for jailbroken iPhones from Jay "Saurik" Freeman, the author and maintainer of Cydia. Veency provides a VNC remote desktop server for your iPhone, allowing you to connect to the shared screen of your handheld from any VNC client (Apple Remote Desktop, Chicken of the VNC, and more).
I downloaded a copy to my iPhone, rebooted and gave it a whirl to see how well it worked using Chicken of the VNC on my Mac.
From first go, it did what it promised: offering tap-interpretation of my Mac-based mouse clicks as iPhone-sourced finger taps. The current mouse position on the Mac was echoed as a small "x" on the iPhone, so I could always see where the virtual finger was.