Turns out it’s just a place for Rowling to sell Harry Potter e-books! She hasn’t allowed the books to be available electronically yet, but that’s about to change and she’s removing the middle man from the equation. She’ll control - and reap the profit from - all e-book sales.
There’s more to it - there’s apparently some sort of geocaching aspect to the thing, where users can find ‘real’ wands hidden in the US and Europe (no wizards in Africa, it seems!) - but it boils down to e-publishing. This could be a platform for Rowling to introduce new Potter universe short stories or novels, which is interesting. And she says that she could use Pottermore to release some of the Potterverse ephemera that she has in notebooks, ie, the stuff that would have been in an encyclopedia.
What Pottermore really is, though, is a big moment for digital publishing. And Rowling is doing it her own way. These are major books for digital publishing, and I bet she sells a TON of copies - I know I’ll throw them on my Kindle (maybe. See next paragraph). This might be a watershed moment in the full scale adoption of digital book readers.
The one question is: what about Kindle? The idea is that Rowling wants to release the books in one universal format, which would be the epub format - which the Kindle doesn’t support. Also, the only way to buy Kindle books is through Amazon, and Pottermore specifically - and I’m sure purposefully - sidesteps that. Will Amazon come begging to Rowling? The Kindle is the digital book leader… right now. That could change, with plenty of competitors nipping at its heels, and Rowling could be the deciding factor.
So I guess that’s interesting, in a gadget sense. Everything else about Pottermore? Snooze.