Amazon announced this week that users of its Kindle eBook platform can now borrow eBooks from over 11,000 libraries around the United States, erasing what was previously one of the few major advantages of the competing Barnes & Noble Nook platform. (The other is color devices, which Amazon is expected to counter later this year with the release of an Android-based Kindle tablet.)

As is usually the case with Amazon, which dominates the eBook market, the Kindle entry into libraries doesn't just duplicate what the others are doing, but adds unique and useful new features as well.

"We're even doing a little extra here," said Kingle director Jay Marine. "Normally, making margin notes in library books is a big no-no. But we're fixing this by extending our Whispersync technology to library books, so your notes, highlights and bookmarks are always backed up and available the next time you check out the book or if you decide to buy the book."

Customers will need to visit their local library's web site to see whether they support Kindle. But based on demand--Kindle support is a frequent question at libraries all around the US--this will most likely happen pretty quickly. Once you find a book you want to borrow, choose the "Send to Kindle" link from the library web site. This will redirect you to your Amazon.com account page, where you can logon and complete the process.

As you might expect, Kindle library borrowing works on any Kindle device (first generation and on), any Kindle app (free for Android, iPad, iPod touch, iPhone, PC, Mac, BlackBerry or Windows Phone), or via a web browser with the new Kindle Cloud Reader.

From the perspective of a library, Kindle borrowing works just like a paper book in that the library can only lend out as many copies as it purchased at one time. And with library borrowing of eBooks already rising strongly before Kindle's entry (up 75 percent year over year), one might reasonably assume it is going to explode now.