Your wish is granted: Outlook 2007 will have that functionality.

Signature
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
>I suggest to implement a functionality for permit at Outlook to use a public
> shared icalendar (eg: shared Google Calendar)