Amazon just announced a 2.5 software update for its Kindle and Kindle DX readers. At the moment, it's rolling out the update to a "limited group" of Kindle users with a general release coming at the end of May. Enhancements include the ability to organize books and documents into "collections," pan and zoom within PDFs, Kindle password protection, larger and sharper fonts, and just what you've always wanted: the ability to "share book passages with friends on Facebook and Twitter." Somebody pinch us.