One of the cool things about digitally-based books is the ability to upload revised content. I recently revised and re-uploaded all three of my books with the newer covers, plus any little typos or formatting glitches I'd found since publication repaired. (I'm a perfectionist, as my poor IT guy* can attest. If I notice a mistake, I'm going to fix it. I don't care how small it is.) Kindle and Nook customers can get the revised copies FOR FREE. Do not repurchase the book - not only is that not required, it doesn't work - it just sends the exact same version of the book you already purchased.
To check that you've got the latest content for BTL, WYA and/or GFY, check these things:
(1) The interior cover photo should match the one on Amazon/BN exactly.
(2) Under About the Author, the very end should show the printed web addresses to my Facebook page, blog and Twitter. If all three of these aren't there, you DO NOT have the latest version.
Amazon is still learning, I guess. You have to call (or email) and ask to have revised content "pushed" to your Kindle. (Good news: It's not a complicated process and should just take a few minutes. It helps if you have the original order number, but if you don't the rep can search your digital purchases and find it.)
Amazon Kindle Customer Service
Barnes & Noble did this right - I LOVE how easy they've made it for customers to get revised content. I tried it with my Nook last night and it worked like a charm:
(1) Go to your Library.
(2) Select the book(s) you want to receive revised copies of and click "archive." (Don't worry, this doesn't delete your books.)
(3) Go to your archived books (under "My Stuff").
(4) Open the book.
(5) Click "Manage" and then "Unarchive." The new version should download automatically.
B&N Nook Customer Service: