\documentclass[a4paper,fleqn,11pt]{article}
\usepackage[T1]{fontenc}
\usepackage{isodate}
%\usepackage[USenglish]{babel}
%\usepackage{ngerman}
\usepackage[english,austrian,american,ngerman]{babel}

\setlength{\parindent}{0mm}

\newcommand{\example}[1]{%
  \selectlanguage{#1}
%  \ifthenelse{\equal{#1}{american}}{\dateamerican}{}%
  \section*{Language: \languagename}
  \begin{tabular}{@{}lll}
    today&normal date format&\today\\
    &isodate&\isodate\today\\
    &numdate&\numdate\today\\
    &shortdate&\shortdate\today\\
    &TeXdate&\TeXdate\today\\
    &back to normal&\origdate\today\\
    another day&normal date format&\printdate{1972-1-30}\\
    &isodate&\isodate\printdate{30.1.1972}\\
    &numdate&\numdate\printdate{1972-1-30}\\
    &shortdate&\shortdate\printdate{1972-1-30}\\
    &TeXdate&\TeXdate\printdate{1972-1-30}\\
    &back to normal&\origdate\printdate{30/1/1972}\\
  \end{tabular}}
\begin{document}
\example{ngerman}
\example{austrian}
\example{english}
\example{american}

\section*{Changed ISO output}
\isodate
\printdate{24/12/2000}

\isodash{--}
\printdate{24/12/2000}

\isodash{$\cdot$}
\printdate{24/12/2000}

\end{document}

