Thats the full VNC client which does that. This uses VNC, however it only sends your input to the remote computer, rather than returning a response to your iPhone screen.
I still don't understand the fascination with using your iPhone keyboard to type out posts here on EIC through your desktop, which pretty much seems to be all its been good for as a proof of concept.
The new additions for Powerpoint look very promising however, I can definitely see a "use" blossoming in that department. Unfortunately theres little use for Keynote in that regards because Mac users have Apple Remote for remote controlling slides.