if you want to match on a specific group and not just the one listed on the user's home dir (which is what i think you're asking for) then this might work:
for I in `ls -1 /home |awk '{print $1}'`;do
if [ "$I" != "lost+found" ]
then
for J in `groups $I`;do
if [ "$J" = "groupname" ]
then
cp <file> /home/$I;
fi
done
fi
done
while not foolproof, it at least skips the lost+found directory, if your home dirs are in a filesystem of their own. you could tweak something like this and place it in a script if the file copy task is something you do on a regular basis.
anyway, hope it helps...