"To counter Amazon.com, Sony and other device makers as well as several publishers will use the same technology, called ePub, for digital book sales..." via nytimes.com
The New York Times reports that Sony announced that they will now support and use the ePub digital book standard. This will help address the issue of not reading digital content on multiple devices. Before this announcement Sony utilized its own format and those digital books could only be read on the Sony device. By the end of the year it will only sell digital book in the ePub format. Should be interesting to see if the rumored Apple tablet device also will support ePub. If so, this might make it difficult for Amazon to keep its own separate format. In the end what I hope happens is that digital content will be independent of what ever device you read it with.