Changeable textbooks

According to the N.Y. Times, Macmillan Publishing company is releasing software that will allow academic authors to change their textbooks after publication. Authors will be able to revise, update, and rearrange chapters to suit the needs of individual courses or new developments. They will also be allowed to insert new material from their other works or from other authors (presumably with the author's permission). This is an exciting new development in publishing form college texts and it's quite possible the trend will be extended to high school textbooks too. Of course there are dangers--new errors could slip into the book as the author makes changes without editorial oversight. I wonder whether there will be any hacking of textbooks to insert material contrary to the wishes of the author. The issue of security is always important for online texts. Overal, however, the possibilities for better, less expensive and more up-to-date textbooks look good. Let's hope this trend continues.