The iPad just celebrated its 60th birthday (60 days, that is). Actually, Apple is celebrating something much more significant; selling its two millionth iPad in that time period.

That's a steady pace of about one million units a month (reminder: Apple hit the one million mark around day 28 after iPads hit the shelves in April).

Also of note; Apple reports there are now 5000 apps just for the iPad.

My friend, Matt, is devoted to two things; Apple anything and my high school buddy, Lauren. Matt, of course, couldn't buy an iPad fast enough. He tells me that after a couple of months he finds he's using his MacBook much, much less and he's completely sworn off taking paper to meetings.

We had an interesting chat the other day about how the iPad and other eReaders will reinvent publishing as we know it. Not the industry, but the book itself. eReaders are a new medium. Just as the early days of television looked like a videotaped version of radio (the previous be-all medium), these are the early days of eReaders. So far, it is largely just digitized hard copy books. At some point, eBooks will evolve into something else with new formats that leverage its medium.

What will the eBooks of the future look like?

I agree with Matt. Textbook publishers will likely figure it out first.