FT on June 23, 2011:
"Developers have not disclosed how much the books will cost. But the FT has established that Sony, a joint venture partner in the site, is developing related products, including a themed version of its Sony reader
Since people can't read the article, I should spell out the obvious - it's about Harry Potter being available in ebooks. It specifies that SONY will be providing the backbone, that the books will be available EXCLUSIVELY on Pottermore but that they will be compatible "with a range of e-reader devices including Amazon’s Kindle, Apple’s iPad, and Sony’s reader".