It seems to be fairly common for a group of users to want a shared contact list
that all of them can add to and modify. While Jimmy May's excellent article,
Sharing Outlook Folders, shows how a user can share personal folders, there's
also a way to make a global contacts list available under Exchange Server by
exploiting the Public Folders feature. I've set this up in our office to replace
an old shared installation of Act! 3.0 and it seems to be working very well for
my users. 

1. Under All Public Folders (which actually lives on the Exchange Server), create
a new folder, Global Contacts, for contact items. The public folder can be
created from either the Exchange Server or a local workstations, but the person
who sets it up must have Exchange Administrator privileges. 

2. Give everyone who will use the folder full Create/Modify permissions by
selecting them from the recipients list either individually or by workgroups. You
may want to limit Erase/Delete permissions to selected users so that they don't
trample all over each other's contacts. 

3. If necessary, import an existing Personal Address Book or outside file (Act!,
etc.) into the Global Contacts folder. 

4. Have each user right click the Global Contacts folder and bring up the
properties dialog. Click the "Show as e-mail address book" checkbox on the
Outlook Address Book tab and close the dialog. 

You should now have a shared global address book.