He needs to consider the end users thought process on using this app.
Why and how they are they using it (entertainment, quick reference, reading through it sequentially like a book?). Then consider how the information can be categorised and cross referenced. He will definitely need to categorise and sub-categorise somehow as you don't want to have lists with large numbers of stuff as even with inertial scroll it rapidly becomes tedious whipping through them. There are also performance considerations on mobile devices with constructing views out of large numbers of elements.
I'm not familiar with the new windows mobile UI conventions, but many information based mobile apps will stick with a standard vertical list that swipes right to another sub list and ends up in a view. The depth into the 'tree' of subcategories can be breadcrumbed at the top with a row of buttons.
At the top level he may want to provide a selection of different navigation methods - chronological, by topic, and a search page with auto suggestion.
Probably worth him wireframing before the build and getting reaction from potential end users. I find balsamiq mockups good for this.