about epub, that's one format we're already committed to supporting. it's listed in the FAQ. we're very careful about not over-promising, that's partly why there aren't more features listed.
edit; really besides the point, but saw your nick. our internal name for the prototype (in u-boot and the kernel) is zero-gravitas.
epub: Yes, email: No :)
Also, there's definitely a balance to be struck between lack of distraction and lack of features. It would be a waste for this not to have an epub reader, for example. But while I'd really appreciate having email on it, that's starting to get into distraction territory.