Originally posted by hpladd
rwt rw rw and rwx rw rwx
Surely you mean
t means sticky, not SUID.
But to answer the question.
The purpose of SUID is to have the executable run as
the owner, no matter who starts it.
The need for it is obvious when an application has
been compiled to require root privileges (and you
don't want to use sudo) and you want a normal user
to be able to run it, e.g. /sbin/reboot ...
Btw, your rwsrw-rw- wouldn't work, the x still needs
to be there for other.