More interesting links found nested within that article:
Live Group Calendar Tools:
Copies all Outlook appointments from Microsoft Exchange Server into a central database and uses Microsoft Internet Information Server to publish it. Users access the calendar and can create meetings through their web browsers. Supports Exchange 2000.
http://www.amrein.com/agendax/
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Enterprise Calendar:
This is a complex sample application that shows how to synchronize data from users' folders to a central public folder automatically. It uses custom forms, Exchange Server script and a .dll created with Visual Basic. Many thanks to Tom Howe, who has demonstrated this application at many conferences.
For Exchange 5.5, click here to download sample code and a white paper explaining the application in detail (479kb, 8 Aug 1999).
Exchange 2000, Enterprise Calendar uses event sinks to resolve some of the limitations in the original version. Click here to download sample code. (477kb, 20 Jun 2001) The included Office Calendar Read Me.doc paper explains the application in detail. Tom's MEC 2000 session is also available -- Building a Group Calendaring Web Application
http://www.slipstick.com/calendar/scheduleall.htm
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There are indeed quite a number of possible tools.
(REMOVE SPACES from the pasted URLs.)
Good luck,
Maxwell