I just got an email from Blair who pointed out a new powertoy addin that he wrote for OneNote 2007. He wrote an addin which will make the current section read-only to prevent others from making edits to the page, here is what he wrote about it:
OneNote ReadOnly Section Addin
I just finished coding a OneNote 2007 addin which will make the currently selected section ReadOnly, so that that section cannot be changed (unless you hit the ReadOnly button again then it will be editable again).
Pretty cool, check it out yourself: OneNote ReadOnly Section Addin. Nice work Blair!