J.K. Rowling is releasing 12 new pieces of Harry Potter content for the Holidays, including a few new stories, and the first tale has been released in the for-pay Pottermore service. To read the story, however, you first have to answer a riddle.
It's not an especially tricky riddle, and it gives some hints about the content of the first story. I won't give the answer here, but be aware you need to type in a specific construction of the character's name.
The writing deals with the town of Cokeworth, where many important characters in the Harry Potter series grew up. It's a short bit of writing, but it answers at least one question and links a few very important events in the books.
I won't say any more in case you haven't read it yet, and I have a feeling Potter fans will be discussing what this means for the lore for a good amount of time.