Chris Pratley asked for feedback on how blogging from OneNote should appear and my comments became too unwieldy for his comments box:
To dispense with two crucial things: ink support and layout support (i.e., not just tables but the arbitrary positioning of elements in X-Y space a la "real" OneNote). AFAIK, there is no blogging tool right now that allows you to draw a map and type "Bob's House" at the appropriate spot; for all the power of Blogging As It Exists, it basically works with text streams.
Now for the more ruminative stuff: OneNote has the metaphor of pages, tabs, and notebooks. The obvious mapping is to blog entries, categories, and blogs. So I would expect that to "subscribe to a blog" in OneNote, I would get a new notebook that periodically updated itself; new titled pages appearing for every new post. Since page titles have limited screen real-estate, this introduces a navigation problem: perhaps one needs some kind of automatic Table of Contents page, essentially providing aggregator services. Or... maybe one doesn't subscribe to a blog in OneNote, perhaps aggregation is the role of NewsGator / Outlook and a OneNote "subscribed to" blog represents posts that one wishes to keep around for reference: one still would have a OneNote notebook corresponding to the blog, but the notebook wouldn't update itself, one would use a SideNote / Snippet sort of capability to shoot entries from the aggregator into the notebook.
So upstream you must support ink and layout, downstream you must support the blog -> category -> entry hierarchy. The third leg of the stool is clearly linking. The feedlink / permalink distinction is the clearest example I know of REST: the feedlink is a permanent resource of "the latest stuff" the permalink is a permanent resource to "this particular thing." I want hyperlinks in OneNote that embrace this distinction and I want those hyperlinks to be able to navigate not only across the World Wide Web (of course) but within my own computer, workgroup, corporation, and social networks. In other words, I want OneNote notebooks to become transparent to deep linking: onenote://machinename/mynotebook/mypage#myanchor as a URI (short of onenote as a complete scheme, I'll settle for a transition period where http is shoehorned into service). Creating good RESTian links must be reduced to a trivial service (with my Tablet I want to be able to circle some elements, make a gesture, and those elements become a post, with a permalink and a reference in the feedlink).
I also want to make a slightly different gesture to free the elements for editing. In other words, the "square" gesture makes a post that only I can edit (a traditional blog entry), the "star" gesture makes a post that anyone can edit (a wiki-like entry), the "circle" gesture makes a post that only people in the "ninja" group can edit, etc.