Share outlook 2007 contacts items and sync it to personal contact under exchange server

Hello fellow experts,

I have a client who has Exchange 2007 and Outlook 2007 on all clients. They have a lot of sales persons, who each have their own personal contact folder where they maintain all of their contacts.
They want to create a centralized folder where all of contacts will be available to all - how ever, they want the users to still maintain their own contact folder, and just sycnronize it now and then to the public contact folder.
For example, person A edits his own contact information, presses a button and then his contact information is compared with the public one, and all changes are transffered to the public one. If conflicts are found, then the person is notified about it.
I do NOT want: Just a public folder that contains contacts - they don't want to edit the public folder directly - they want each person to maintain their own folder, and just sync it to the public one.

I found an application that roughly does what we need:
http://www.infoware.ca/content/tcon.asp?fullpage=1
However, they do not support 2007. Is that because in 2007 there is a method of doing it out of the box that I don't know of?

Thank you for your help!