epilogue:
Yes, the .command suffix trick works with 10.1.
I didn't see bash on 10.1, just sh.
No, didn't need to mess with "Folder Actions" -- though
I think they are AppleScript-only.
Regarding sudo, I wrote one script that does all the
work calling chown, and then a 2nd script that calls
the first as: 'sudo /path/to/first/script.sh'. The
2nd script ends in .command, can be double-clicked
(via an alias on the user's desktop), and prompts
for a password. Nice.