Amazon announced the upcoming release of Kindle (and Kindle DX) Software Update Version 2.5 on their website this week. The updated software will first be released to a small group of Kindle users, with a full launch planned in late May 2010. Among the new features will be the ability to share passages of your favorite books with friends on Facebook and Twitter, and zoom or pan around PDF documents for easier viewing. The highlights of the new features listed on Amazon’s site are as follows:

• Collections: Organize your books and documents into one or more collections.
• PDF Pan and Zoom: Zoom into PDFs and pan around to easily view small print and detailed tables or graphics.
• Password Protection: Password protect your Kindle when you’re not using it.
• More Fonts & Improved Clarity: Enjoy two new larger font sizes and sharper fonts for an even more comfortable reading experience.
• Facebook & Twitter Posts: Share book passages with friends on Facebook and Twitter directly from your Kindle.
• Popular Highlights: See what the Kindle community thinks are the most interesting passages in the books you’re reading.

The updates will definitely increase the usability of the Kindle, though some users will not be able to take advantage of the new features. CrunchGear reports that the new software will not work with first generation Kindles. In the coming weeks, Amazon will be providing updated information on the release schedule. Visit Amazon.com for the latest Kindle news.