Dear Jeremy,
On this site is an article on various ways to share Outlook data:
http://office.microsoft.com/en-us/assistance/HA011477571033.aspx
You will also find a list of third-party sharing tools:
http://www.mapistore.com/Outlook/Groupware
http://www.slipstick.com/outlook/share.htm
--
Oliver Vukovics
Share Outlook without Exchange: Public ShareFolder
Notebook Synchronisation for Outlook: Public SyncTool
http://www.publicshareware.com
> Does anyone know of a program to make it possible for several users to
> connect to one Outlook-PST file at the same time?
>
> Thanks.
> Jeremy