A Brief but Important Update:
Pottermore has released chapters eight through fifteen of Harry Potter and the Prisoner of Azkaban. Visit Pottermore.com and explore the new chapters.
From the Insider post:
We are excited to announce that the next instalment of Harry Potter and the Prisoner of Azkaban is now ready to explore. In this instalment you will witness a re-enactment of the beheading of Nearly Headless Nick, learn about the ancient wizarding game of Gobstones, pick up sweets in Honeydukes and see the ‘most haunted dwelling in Britain’ – the Shrieking Shack.
Pottermore also announced that with these new chapters, a new “Spoiler Alert” feature has been set into place.
For the first time, some of the new Moments have been released with accompanying audio book snippets for our UK, US and German users. We have also introduced a new spoiler alert feature on selected exclusive entries from J.K. Rowling. If you are about to read anything that may give away storylines or information from beyond that particular Moment on Pottermore.com, an alert will appear. You then have the choice to continue reading or to navigate away and come back at a later time so as not to spoil your own journey through the stories. You can disable the spoiler warning any time it appears and manage your spoiler settings in Account Settings.