"Sony is still in the game."
“We don’t believe in walled gardens. We believe in an open format, the EPUB format, so that all our content can be read on future devices. It’s very important for our customers. We believe in giving people open access to our Reader store with different hardware from different manufacturers.”
Sony is strategically positioning themselves for the long-term in ebooks. The others can have their proprietary formats on their proprietary devices - at least as long as their corporate friends say they can.