Microsoft has stated that the document aspects of WPF/E and the clear type typography that supports it will not be included in WPF/E because of the targeted download size. Apparently the typography includes a lot of data for things like kerning, ligatures, and word breaks that would add several megs to the size of the download.
Blackice
Posted: Silverlight (formerly WPF/E) General Discussion, FlowDocument coming to WPF/E?