To have completion with bash you can use this:

  function _jump {
      local cur=${COMP_WORDS[COMP_CWORD]}
      local marks=$(find $MARKPATH -type l -printf "%f\n")
      COMPREPLY=($(compgen -W '${marks[@]}' -- "$cur"))
      return 0
  }
  complete -o default -o nospace -F _jump jump

Bash completion really needs better docs :-|