Originally Posted by HarryT
The Sony doesn't particularly support a lot of different file types. It's an ADE device, like pretty much every other reader (except Amazon) on the market is, hence it supports ePub and PDF. It has rather limited support for plain text and RTF. That's pretty much it.
Oops. What I should have said is that a lot of other ebook store sell books that are directly supported by the sony readers (Adept EPUB).