She includes a chart of the DRM compatibilities between the Nook, Sony Reader and Kindle, and, of course, nobody is compatible with anybody else. The Sony and Nook can read Epub, of course, but it’s the DRMed Epub books that cause the trouble. The Nook can’t read Sony DRM and Sony can’t read Nook DRM and, of course, the Kindle can’t read either and “either” can’t read Kindle DRM and now Apple is saying it will have its own DRM that Kindle and Sony and Nook can’t read. I’m sure it’s all very clear to you now, especially since they are, almost, all using the new “industry standard” Epub.
R I D I F U C K E N C U L E !