I have a folder "share"
eipe@eipe-john:~$ ls -l | grep share
drwxrwxr-t  2 eipe dev    4096 2010-12-13 21:07 share
and in share I have a executable file list.sh
-rwsr-sr-- 1 eipe egroup  3 2010-12-12 18:35 list.sh
There are 2 users in the picture - "eipe" and "tom". Both are member's of "dev" group.

I read that if setuid bit is set on a executable file it causes the program to run as it's owner, no matter who executes it. But when tom tries to run list.sh
tom@eipe-john:/home/eipe/share$ ./list.sh
bash: ./list.sh: Permission denied