You can do that by granting Author permission on the Calendar folder only to
the people you want to have direct booking privileges.

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Sue Mosher, Outlook MVP
Author of
Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
>I have setup several resources like conference rooms and such and I would
>like to restrict permissions to book these resources
> and only give certain users rights to book.
>
> how can this be done?