10.6 made the computer prompt for a password when deleting something out of /Applications like you describe, so I wonder if there is some common thing people were doing or some common mistake people were making that was causing folks to accidentally delete applications. I sure would like to know how it happens.
Easy. Just remove the sticky bit from /Applications. You only have to follow someone's advice to use
chmod 775 /Applications one time. (It should be
chmod 1775 /Applications to set the sticky bit.)
But you don't even have to use Terminal. In Finder, Get Info on /Applications, click the + button to add your user to the permissions list, and give yourself read/write access. Finder responds by adding a new ACL that, among other things, grants you delete_child rights. ACLs trump standard Unix permissions, and the sticky bit on /Applications isn't even noticed.
Or even more simply, just grant everyone read/write access in Get Info. Finder removes the sticky bit when you do this. Once it's gone, Finder never puts it back.
