TeX and other traditional text layout markup languages are predicated on the assumption that the final output format would be known to the nanometer. Extensive computation and clever algorithms let us optimize the presentation for a high standard of quality. But ebooks are here. The iPad has sold more than two million units in under three months, and, combined with other book readers, offers a new way to store and read documents. While these readers offer hope to newspapers (and perhaps doom to many physical bookstores), they are an increasing challenge to high quality text layout. Ebook users are accustomed to selecting text size (for aged eyes and varied reading conditions) and reader orientation. We can’t run TeX over a document every time a reader shifts position. Do we precompute and download layouts for various devices, orientations, and text sizes? Do we compromise our standards of quality to use HTML- and XML-based solutions? These are new challenges to the TeX community.