Google has launched its long-awaited e-bookstore, Google E-books, bringing more than 3 million books — many of them free — to any device with a web browser in the U.S Google claims that its service is “the largest e-books collection in the world with more than three million titles including hundreds of thousands for sale”.

Unlike the iBookstore, which is limited to iOS devices, Google's eBooks is available on a host of platforms - including laptops and tablets to smartphones just like Kindle, giving it a competitive edge over Apple’s iBookstore.

Google had this to say on their blog:

    We designed Google eBooks to be open. Many devices are compatible with Google eBooks—everything from laptops to netbooks to tablets to smartphones to e-readers. With the newGoogle eBooks Web Reader, you can buy, store and read Google eBooks in the cloud. That means you can access your ebooks like you would messages in Gmail or photos in Picasa—using a free, password-protected Google account with unlimited ebooks storage.

Google has also released the Google Books app in the Apple App Store, which is compatible with the iPad, iPhone, and iPod touch. Note that your iDevices should be running iOS 3.0 or above to be able to run the app. Using the app, users can read books purchased from the Google eBookstore while on the go.

Nearly 4,000 publishers will be providing content through Google E-books at launch, including all of the major players: Random House, Macmillan, Simon & Schuster, Hachette, etc.

Here is the list of features available:

iPhone / iPod touch app details

* Stores up to 8,000 titles on average (based on 16GB model)
* Recommended for iPhones with 256MB memory or above
* Mobile eBookstore
* Search within book
* Adjust text size, typeface, line space
* Night-reading mode
* Free samples of books
* Information about book
* Offline reading
* Worry-free archive

iPad app details
* Stores up to 16,000 titles on average (based on 32GB model)
* Native iPad interface app for optimal reading experience
* Mobile eBookstore
* Search within book
* Adjust text size, typeface, line space
* Night-reading mode
* Free samples of books
* Information about book
* Offline reading
* Worry-free archive

Open Google E-books » 

You can checkout the introductory video of Google eBooks below: