[jocampo]

It is really silly keep arguing about formats when we all know the issue is not that but the DRM implementation.

For a regular novel or book without images or complex layout, they both (mobi and ePub) serve well as ebook format. Without companies putting restrictions on top of that, people would be able to buy from any company, regardless of the ebook reader they bought or have. But again, it's about business and money and of course, Sony and B&N are not the exception.

Imagine a CD (same one) being sold by Sony, Amazon and B&N, but won't play unless you buy the company's player. It's basically the same. They want you to buy ebooks from their store, to make more money!