For the record, it was a cord to push the video out.
No, at present (one should ALWAYS use the term "at present" when discussing some perceived shortcoming of the iPad) there is no way for the *iPad* to send video to a projector projector wirelessly. I'm not aware of any OTHER devices that do this either, so I'm not sure I would call this a "shortcoming."
As for controlling a slideshow that is playing *on* an iPad, there are wireless options galore that exist right now. "Keynote Remote," a 99¢ app from Apple, allows any iPhone to be used as a wifi remote to keynote, and this will almost certainly be updated to work with Keynote running on an iPad. In addition, third-party apps can replicate this functionality right now -- today -- for other applications, and again it would be trivial to update them to work on the "the iPad version" of those apps.
Indeed, this very topic is exactly the main reason I want an iPad. Why should I carry a laptop to presentations anymore? I'll have a projector, an iPad with Keynote, and Keynote Remote on my iPhone. Should be all I need, even including being able to demo "desktop stuff" via BackToMyMac or demo websites etc right on the device. It shaves about four pounds off this road warriors' load, plus can be used in Coach seats, and much easier to store.
From the point of view of a professional presenter, this thing is all WIN and no FAIL.
