Terry McGraw, the chief executive of McGraw-Hill & Co., appears to have let the cat out of the bag, confirming the existence of the Apple tablet on national TV.Appearing on CNBC following the company's earnings call, McGraw was asked about the possibility about putting his company's materials on the Apple tablet. It's the kind of question journalists ask, without really expecting to get an answer, especially one being broadcast live to millions of people.Pay dirt. And not just a vague confirmation, but even a spec!"Yes, very exciting. Very exciting. They'll make their announcement tomorrow, on this one," McGraw said. "We have worked with Apple for quite a while, and their -- the tablet will be based on the iPhone operating system, and so it will be transferable. So what you're going to be able to do now-- we have a consortium of ebooks, and we have 95 percent of our all materials that are in ebook format on that one so now with the tablet you'll going to open up that market the higher education market, the professional market. The tablet is going to be just really terrific."McGraw's confirmation itself confirms that the tablet will be an e-reader of a sort, and targeted at the vertical markets.The Apple quote begins at just about 2:48 in the clip.

Credit MacRumors with discovering the leak.