ahiliation@debian:~$ chmod +t source/
ahiliation@debian:~$ ls -l
total 12
drwxr-xr-x 2 ahiliation ahiliation 4096 2010-03-13 04:40 Desktop
drwxr-xr-x 2 ahiliation ahiliation 4096 2010-03-13 19:20 Downloads
drwxr-xr-t 2 ahiliation ahiliation 4096 2010-03-13 20:41 source
t - Save text attribute (sticky bit) - The user may delete or modify only those files in the directory that they own or have write permission for.
http://www.comptechdoc.org/os/linux/usersguide/linux_ugfilesp.html