After more than a year since we first heard the rumors, Google has entered the world of e-books. Today, the company launched its e-book marketplace with more than 3 million titles on the shelves that will be available to nearly anyone with a smartphone, laptop, tablet, netbook or desktop computer.

Previously thought to be called “Google Editions”, the “Google eBookstore” is live and offering hundreds of thousands of titles for purchase. As opposed to other e-book providers, Google’s e-books are entirely cloud-based.

“Google eBooks stores your library in the digital cloud,” writes the company, “so you can read all of your favorite books using just about any device with an Internet connection.”

For those of you worried about reading your books on the go or up in the air, where there might be no Internet connection, Google says that “once you open your book using our mobile reader apps, your book will sync to your device and you can continue reading it online or offline.”

As for accessing these books, Google supports a number of devices, from Android and iOS smartphones to any e-book reader that supports the Adobe e-book platform to any device with a Javascript-enabled browser. Along with reading e-books, there is a Google Books app for both Android and iOS devices, which not only let you read the books, but make e-book purchases on the go.

Google’s e-book initiative was first expected to launch last summer, but it has been held up by several legal and technical hurdles. Now, it looks like it got here just in time for the holidays, although there is no readily apparent way to buy a Google e-book as a gift. This is a feature that just came to Amazon’s Kindle, after all, so it might not be available at launch. For now, Google’s e-books will be available through its online store, mobile apps, and through Powell’s Books, Albiris and participating members of the American Booksellers Association.

A common speculation is that Google’s device-agnostic entry into the e-book market is going to be disruptive and take a chunk of users and revenue from Amazon. What do you think? Will features like e-ink be enough to stave off the Big G or is a cloud-based, device-agnostic offering going to change e-books forever?

mike melanson