Kindle users soon will be able to share book passages with their online communities like Twitter and Facebook. Amazon announced an automatic software update for the Kindle in the form of Kindle software verison 2.5. The new over-the-air update will roll out to a limited group of Kindle users with plans for a broad release in late May.

Aside from Twitter and Facebook support, the new update includes the ability to organize books into collections, PDF pan and zoom, password protection for the device and more font choices.

In the wake of Apple’s recent launch of the iPad, it appears there’s a bit of a race to add functionality to existing eReaders like Barnes & Noble’s Nook and the Amazon Kindle. Just last week, Barnes & Noble added the ability to access a collection of Android apps on the Nook.

Both the Kindle and the Nook get their 3G connectivity from AT&T.