Just found this awesome post regarding scripting Onenote 2007.

http://bdewey.com/2007/07/18/onenote-powershell-provider/

Maybe I'll think of my own custom solution for using Onenote now...

Onenote 2010 should be out any time now.

Back when I was heavy into OneNote, I really liked this site: http://www.onenotepowertoys.com/

But as I recall, all of the extensions only worked on ON2003 and 07 killed them.