As GalleyCat reported yesterday, a glitch yesterday afternoon temporarily caused all the buy buttons for Kindle e-books to disappear. All titles were listed as not available to customers in the United States. Amazon corrected the "website issue" quickly, and the buy buttons were restored. No word on whether the glitch was connected to yesterday's release of the Harry Potter e-books, which are some of the only e-books that aren't purchased directly on Amazon's Website: instead of having a buy button, they have a "Buy at Pottermore" button and the following statement:

"Harry Potter Kindle books can be purchased at J.K. Rowling's Pottermore Shop, a third-party site. Clicking on 'Buy at Pottermore' will take you to Pottermore Shop, where you will need to create a separate account. Like all Kindle books, books purchased from Pottermore are "Buy Once, Read Everywhere" and will be delivered to your Kindle or free Kindle reading apps"

The Harry Potter e-books have been featured on Amazon's front page since yesterday.