When Pottermore got started, this blog was a way for people who had not yet gotten their letters to take advantage of those who had. Now that Pottermore is open to the public, it's more of a glossary, a compendium of all the exclusive new content in Pottermore, all in one easy place.
You'd think I wouldn't need to say it, but if want to experience Pottermore for yourself without it being spoiled, DO NOT READ ON. Obviously.
Catching Elephant is a theme by Andy Taylor
From Chapter 18: Dobby’s Reward
From Chapter 16: The Chamber of Secrets
Chapters 5-11 of the Chamber of Secrets are now available to be explored on Pottermore.
From Chapter 4: At Flourish and Blotts
From Chapter 10: The Rogue Bludger
From Chapter 3: The Burrow.
As of Wednesday, July 11th the second book, Harry Potter and the Chamber of Secrets, is open on Pottermore.
EDIT: Only the first four chapters are open.