Here's an interesting thread - says a senior official was avoiding using prompters b/c of cost, but tried this iPad app.
On the one hand, it might be great to have the script scrolling on an iPad/iTouch setup especially for public speaking where looking at a podium is totally acceptable.
Sometimes, actors also need to have some dialogue placed for them, like if someone has to stand in - I can see this working really well. I was on a production recently that could have used an iPad setup, placed neatly say, behind a vase, with the talent reading off of it.
Of course paper is the best/cheapest medium and sometimes, if the actor isn't on-book, you can just stick the pages in the talent's hands. But you'd have to be careful that the actor isn't going to be self-conscious and trying to compensate for it.
Again - not ideal, but a possiblity.
http://www.dvinfo.net/forum/open-dv-discussion/491768-cut-notes-timecode-notes-ipad.html