I use GNU screen a lot with zsh as my shell.  It would be a nice feature (I think) to be able to display the current directory name (not the full path) as the tab title.  I can do that with CTRL+A SHIFT+A but that is manual.  I would like it to change whenever I change directory.
Does anyone know of a way to do this?
Edit: The answer also feature the solution for bash.
 
                