Originally Posted by nekokami
Good move on the social DRM decision. I'd suggest looking at ePub, which is rapidly becoming the most widely supported format. It will allow your pages to reflow on different sized screens, which PDF won't. That way, if a user can't afford the most optimal reader, e.g. the V9t, they can still read your content on whatever they do have.
As a publisher designing a book for a particular customer using PDF you should think about publishing the eBook in the exact size needed by the customer so that it will work on 6" screens or whatever he/she has.