So I do appologize if I am repeating someone, but I didn't feel like going through all 7 pages. In short... HERE IS THE ANSWER... And it works really well.
My set up. MacBook Pro 17" running OSX.
Currently iPad1 (2 soon I hope)
I've bought a $2 app for the iPad called "DisplayPad" and it's free Mac App counterpart. It allows me to use my iPad as if it were an external monitor as an extended desktop.
NOW... when you open Keynote and begin your display, not only can you control it, but you can see "presenter mode" on the iPad including the next slide, timer, and even your notes.
I set up my Laptop at the projector. Create a computer to computer Wifi Network between the Mac and the Ipad and there it is!
It is GREAT!
At this point the only flaw I can see is that in order to engage the connection, you have to do it from the mac. If you mistakenly close the DisplayPad app on your iPad, you need to go back to the laptop in order to re-establish the link. Kind of a bummer when the Mac is being displayed on a projector and you are on stage! Just be careful to not do that.
OH.. and make sure you run the projector as a Mirror of the Laptop or you will have issues with them running as 3 montiors and confused as to what goes where.
I've been doing presentations with ProRes 422HQ video in them and it runs Flawlessly. Audio and video play smoothly and then end with the next slide ready to go.
Hope this is helpful!
I realize this isn't the full point of the disscussion and YES I know that it was a request to control the iPad, but this is a better solution if you have the ability.
Just my 2 cents.