I was basically trying out the keynote on ipad + iphone as clicker app in class today. Worked great, but I seemed to take a lot of time for the prep work.Actually, there is. Check out the Kingston Wi-Drive, Maxell Airstash or Seagate Satellite. They basically amount to wireless flash drives. And you don't need an existing wifi access point because they all can act as access points themselves. It seems like with this solution you wouldn't even need to convert PPT to Keynote (although have you considered apps like Docs to Go or Quickoffice).
I will try to find time to get round to trying them out. Thanks for the heads up. Perhaps I have been going about it the wrong way. Seems the ipad is turning out to be a fairly expensive toy/investment. Got the most expensive model, now still having to shell out for monthly internet bill, screen protector, casing, misc apps, attachments and so on...