Below is a little code I use with ksh. The wt() function can only be expected to work in an X-term. The code sequences are different for other terminal emulators.

DIRSTACK=$PWD
function dirs {
  print $DIRSTACK
}

function pushd {
  dirname=$1
  cd ${dirname:?"missing directory name."}
  DIRSTACK="$PWD $DIRSTACK"
}

function popd {
  DIRSTACK=${DIRSTACK#* }
  top=${DIRSTACK%% *}
  cd $top
}

function rfind
{
  dir=$PWD
  while [ ! -e $1 ]; do
    if [ $PWD == "/" ]; then
      command cd $dir
      return 1
    else
      command cd ..
    fi
  done

  rfdir=$PWD
  command cd $dir

  return 0
}

function wt
{
  printf "ESC]0;${@/$HOME/'~'}^G"
}

function git_dir
{
  typeset str
  rfdir=""
  rfind '.git'
  if [ $? -eq 0  ]; then
    str="\{`git branch | grep '*' | cut -d ' ' -f 2`\}"
    wt "[${rfdir}${str}]"
  else
    wt "xterm"
  fi

  echo "$str"
}

function mkprompt
{
  typeset branch

  branch=`git_dir`
  PS1="${branch}$ "
}

function cd
{
  PS1="$ "
  command cd $@
  mkprompt
}