From the Wall Street Journal:
Users will be able to buy books through books.google.com/ebooks and read them on many devices, including tablets, computers, smartphones and open format e-readers. Google on Monday released e-book buying and reading apps for Apple’s iPhone, iTouch and iPad as well as Android mobile devices.
Customers will be able to store their Google-purchased titles online on their own bookshelf accessible via their Google account. They will be able to start reading e-books on one device or computer and switch midway through the book to other devices without losing their spot, Google engineers said.