Okay, silly title but I couldn't resist. :) I'm a big fan of OneNote, and after exploring the features and a trial run of using it as my sole source for note taking, I became hooked. Actually, I don't remember the last time that I even carried an actual notebook around.
There are a couple of other consultants that I work with that utilize OneNote as well, and there are times that we share notebooks with each other. It never occurred to me to think of storing shared OneNote Notebooks in SharePoint until I saw this article by Thomas from Microsoft Consulting Services: http://blogs.msdn.com/mcsnoiwb/archive/2008/12/03/onenote-and-sharepoint-the-basics.aspx. Simply brilliant!
Thomas explains the following, and a must read for anyone wanting to share their Notebooks with team members.