And here we go with the confirmation. Just a day before the official announcement, we have a confirmation on the tablet’s existence (as if we weren’t already aware), and now we know the tablet will run the iPhone OS, as expected.

McGraw-Hill Chairman and CEO Terry McGraw confirmed that Apple will reveal the tablet tomorrow in a live interview to CNBC.

“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 percent of all our materials that are in e-book format on that one. 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.” [CNET]

As CNET rightfully points out, Steve Jobs must be fuming mad with McGraw taking away from Apple’s main launch event tomorrow by revealing the OS. Oops!