The Pew Research Center's Internet & American Life Project has released Libraries, Patrons, and E-books .
Here's an excerpt:
Some 12% of Americans ages 16 and older who read e-books say they have borrowed an e-book from a library in the past year. . . .
But most in the broader public, not just e-book readers, are generally not aware they can borrow e-books from libraries. We asked all those ages 16 and older if they know whether they can borrow e-books from their library and 62% said they did not know if their library offered that service. Some 22% say they know that their library does lend out e-books, and 14% say they know their library does not lend out e-books.