Well, since ManyBooks.net manages to put their content into a Reader compatible format, I'd guess that Fictionwise could too, the sticking point would most likely be that Fictionwise would want to have some way for their DRM to work with the stuff they sold in that format. I don't know what would be involved in that, or even if Fictionwise would want to mess with it in the first place.
In any case, it wouldn't hurt to ask, I suppose.
