I mean that in a good way, of course. EPUB is the only e-reader-compatible file format (of the 30 or so floating about) that seems to make real sense for education and has enough industry traction to make a dent in e-textbooks. Sony's announcement that its Reader products would standardize to the format with third-party DRM as needed tipped the scales further in EPUB's favor.
Now, according to PC Magazine,
Google's massive supply of public domain books just got a bit more portable. The company today announced that it would be releasing more than one million books in the format, which is compatible with the iPhone, Android handsets, and e-readers from Sony and Plastic Logic.
This should be on the order of one million books, free from DRM and usable on any number of devices (except, at least natively, the Kindle). Perhaps the greatest advantage of EPUB for students, though, is the ability of the book text to "reflow" on a variety of devices. While this doesn't solve the image problem of textbooks, it makes a whole lot of books readable on everything from an iPod Touch to a netbook to a full-blown laptop. It also makes the books more accessible to visually impaired students because of the ease with which text can be resized.
The Google Book Project had previously used PDFs for storing and disseminating its public domain documents, but PDFs obviously don't render well on very small screens. According to Google's blog,
By adding support for EPUB downloads, we're hoping to make these books more accessible by helping people around the world to find and read them in more places.
Sounds good to me!