E-books aren't going to replace books. E-books are books, merely with a different form. More and more often, that form is ePub, a format powered by standard XHTML. As such, ePub can benefit from our nearly ten years' experience building standards-compliant websites. That's great news for publishers and standards-aware web designers. Great news for readers, too. Our favorite genius, Joe Clark, explains the simple why and how.