Well - I did it today.
I had a PowerPoint file to use for a presentation. I created a movie of the file, converted it in Quicktime for the iPhone, synced it to my phone, and headed off to the meeting. (With a copy of my presentation on a usb pocket drive, just in case...)
At the meeting I plugged into the provided projector with my composite video cable, and then played the ppt movie from the iPhone. I used the pause button on the phone to control the pace of the presentation. It was way cool, and a big hit with everyone at the meeting.
To be honest, everyone was so impressed with the iPhone I'm not sure they were listening to the presentation... (grin)
Hey what program did you use to convert ppt to a movie file?