No, not in a PST setup, but in an Exchange environment. The OP didn't
specify his setup, so I should have qualified my response
appropriately. My bad. ;]
Ray at work
Not in Outlook you can't, there is only one file containing ALL the
Outlook folders don't forget. You can set permissions on the pst as
a whole using the OS. I think what the OP was after is protecting
some folders within the t itself.