The ipad will be more valuable to educational content once it is flash enabled. (While you don't see the video in the textbooks, obviously, most publishers provide some sort of video online that accompanies the program.) Having both at their fingertips will be an enormous advantage for students - which is needed to make the ipad a valuable tool for education.
Anne, I wouldn't hold your breath for Flash on the iPad or any other iPhoneOS device. On Mac OS X and iPhone OS, Flash is a huge resource hog and has been cited as the most frequent cause of browser crashes. I think Apple is biding their time waiting for HTML 5 to become more fully supported and Flash to become increasingly less relevant.
The lack of Flash on the iPhone hasn't hurt iPhone adoption and hasn't kept the iPhone and iPod Touch from becoming valuable tools for education. The limiting factor for iPhone and iPad adoption is the network - AT & T. As far as content goes - textbook, web, etc - content creators are going to go where the users are - currently, the iPhone platform. They are going to adapt their content for that platform. If that means they have to move away from Flash or develop alternative non-flash based content, that's what they'll do. It's already happening.