Amazon has announced a major software upgrade for the kindle. Version 2.5 of Kindle's software is being rolled out automatically on a limited basis. Adds Facebook and Twitter features to the ereader. Users can now highlight a passage from a book they are reading and hen share the same with their friends on Facebook and Twitter.
The version firmware 2.5 also boasts a bevy of other features like crisper text, larger fonts, organize books into collections, PDF docs get zoom and pan features and password protection.
With competition heating up from the Nook and the release of the iPad. Amazon has had to come up with new features. We can be sure that future updates are going to come with more sharing options for social sites.
Currently users can share content from a book on Twitter and Facebook but with devices like the iPad you get more options and Kindle might well get full social features in the future.