If you are interesting in partnering with an E-Ink device, then the Astak Mentor will run WinCE and they have a
SDK.
Is this actually going to run on the device? If not, then
FeedBooks is a good example of a server-based delivery system that targets multiple ebook formats. They also have custom client software for the iLiad and various techniques for a client to access content. For example, on some devices a web link in a MobiPocket ebook can be used to download a new ebook.