As I posted earlier you can find the 2007 Office System: XML Schema Reference (Beta 2) available online. This download includes the bare-bones information regarding the OneNote 2007 XML Schema that was released for Beta2.
I wanted to make a quick post and give everyone a heads up: if you develop anything with the betas of OneNote 2007 you will need to change your code to have the final OneNote 2007 namespace (when OneNote 2007 goes to market).
For example right now the OneNote XML schema name space is this:
So if you are importing anything into OneNote you need to have this in your XML and if you export anything with OneNote 2007 Beta2/B2TR that is what the output XML will contain. This is the beta version of the namespace and it will be changed. The plan is to have the final namespace be:
However this could change, though I doubt it. Just a heads up if your code works great with B2TR and then doesn't import into the final version of OneNote. Also make sure that if you store any XML of OneNote pages (not recommended) that you get them into OneNote before the final schema changes. Let me know if you all have questions!