Google to sell eBooks by year's end
You'd have offline access through "cached versions" in your browser. In other words, it looks like you'll be able to read eBooks in a browser and save them using Google Gears, which all sounds a lot more awkward and inconvenient than simply downloading a book that you can read on your smartphone, PDA, computer, or eBook reader. Google is trying to make this sound like a good thing, since you'll be able to access the site from any device with a web browser and internet access, but I'd rather have offline access and the ability to save my books to a hard drive or backup media.
Google also wants to differentiate itself from Amazon, which sets its own prices, by allowing publishers to set prices for digital editions of their books.