OneNote 2007 has a cool new feature where you can share your notebook with others in a live setting.  They call it a Live Share Session.  To host a live sharing session, you select the section you want to share (you can't just share one page), and go to the Share menu item.

This will open a Start Live Session toolbar on the side.  You can then optionally enter a password which will be required by users after they go to a session.  You then select Start Live Session.

Once that is complete, the Current Live Session toolbar is shown where you can invite participants via email.

When you click on the Invite Participants link, a new email message will open with an attachment of the shared one note file.

When the invited participant recieves the email, they will be entered into the Live Sharing Session and their email will show in anActive Participants window.  You can allow editing by the participants if you are hosting the session.  I found that this is a little obtrusive though and really only allows for one person at a time to edit.

This is a really good way to share white boards virtually.  You can find out more information here: http://office.microsoft.com/en-us/onenote/HA100907501033.aspx#2.