Amazon Updates Kindle With Facebook and Twitter Support

Amazon just announced the next major update to its Kindle software, version 2.5. It's about to start rolling out to some users, to see a full rollout in May (pretty sure it's already May, Amazon--check your farmers' market. They'll be selling asparagus. May.). This is the second major firmware update to an ebook reader post-iPad--Barnes & Noble released theirs a few weeks ago. 

So what does Amazon bring to Kindle version 2.5? There's "collections," which seem mostly like folders to me--you...