On CNBC today, McGraw-Hill CEO, Harold McGraw III has outright confirmed the Apple iPad announcement that is taking place tomorrow. He goes on to say that it’ll run an iPhone style OS (iPhone OS 3.2) and that it’s just “terrific”. McGraw-Hill will be one of the major book publishers to offer ebooks on the iPad.

“Yeah, Very exciting. Yes, they’ll make their announcement tomorrow on this one. We have worked with Apple for quite a while. And the Tablet is going to be based on the iPhone operating system and so it will be transferable. So what you are going to be able to do now is we have a consortium of e-books. And we have 95% of all our materials that are in e-book format. So now with the tablet you’re going to open up the higher education market, the professional market. The tablet is going to be just really terrific.”

Update: The iPad does indeed run a iPhone-like OS. And to help kick off the release of the iBooks Store, Apple has partnered up with 5 major book publishers including, Penguin, HarperCollins, SIMON & SCHUSTER, macmillan (Part of McGraw-Hill) and hachette. With more to come.