Microsoft has a reader (pdf-like) application SDK?
I just noticed this article from Information Week where they indicate that the New York Times and the Seattle P-I amongst other newspapers will be offering their news in an electronic format based on WPF.
This is all pretty interesting because it really makes sense in terms of competing with Adobe Reader. WPF picks up where reade left off, allowing for customers to roll their own custom applications that can protect and display content on all Windows PCs. Here's to hoping that I won't have to deal with the clunky pdf interface in a few years.