You could do this through the restricted software architecture also. This is how we stopped kids from using Screen Sharing in Leopard. Just have Casper kill the app if it is opened by a user other than the ones we allow.

John
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John Wetter
Technical Services Manager
Educational Technology, Media & Information Services
Hopkins Public Schools

I realize I will not be answering your question and I hate when people do
that to me….but I am going to do it anyway. ;)

I set the permissions to 770 on /Applications/Utilities so that only admins
can open it up. This may be an option for you, just don't do it recursively
because it breaks some of the apps in there.

Ryan M. Manly
Glenbrook High Schools
? ACSP ? ACMT