????Expected since early summer, Google is now in the eBooks business.

????Google (GOOG) opened its eBook store today. While it isn't called "Editions," as was widely reported, much of the other expected details about the new service were correct. Google calls it the world's largest selection of ebooks. The branding is a little confusing as Google shifts frequently between "books," the generic "eBooks," and "eBookstore."

????Google's eBooks is a Cloud service. You don't need a dedicated application or device to order or read books. Because it exists in the Cloud, you can use a browser for reading.

????Users' books are tied to a Google account. Google hooked me (and everyone else) up with three freebies to start:

????There are hundreds of other free, out of circulation classics available here. There are also lots of out of print magazines and newspapers available for free.

????After comparing a few randomly selected books, it looks like Google's prices are often lower than Amazon's (AMZN). Google has said it will support the Agency model, where publishers set the price, and the generic model where Google decides.

????While eBooks are available in a web browser, there are apps for mobile and offline reading. Interestingly enough, the Android-powered Barnes and Noble (BKS) Nook is one of the devices that can be used to read Google Books. So are Sony (SNE) eReaders. Google has incorporated the popular Adobe eBook platform

????Google eBooks is compatible with any dedicated ebook reader that supports the Adobe eBook platform, including the Barnes & Noble Nook? and Reader? from Sony. With just a few steps, you can start reading over 3 million Google eBooks on the go.

????Here's a full list of Adobe eBook Platform supported devices.

????That's pretty much everything but the Kindle.

????I think Amazon should be worried.