\documentclass[a4,landscape,mathcal]{seminar}

\usepackage{graphicx}
\usepackage{fancybox,fancyhdr}
\usepackage{a4}
\usepackage{latexsym}
\usepackage{pstcol}
\usepackage{semcolor,semlayer}
\usepackage{epic,eepic}
\usepackage{amssymb,stmaryrd,euscript,german}

\pagestyle{fancy}
\lhead{\tiny Vortragender}
\chead{}
\rhead{\tiny Titel}
\lfoot{\tiny Noch irgendetwas wichtiges}
\cfoot{}
\rfoot{\scriptsize \thepage}
\renewcommand{\headrulewidth}{0.4pt}
\renewcommand{\footrulewidth}{0.4pt}

\newpagestyle{nichts}%
  {}{}%

\definecolor{darkgreen}{rgb}{.1,.5,.1}

\begin{document}

\begin{slide}
  \slideframe{none} \pagestyle{nichts}

\begin{center}

  \textcolor{blue}{\Large \bf  Titel} \\[1cm]
  Autor \\[4mm]
  {\footnotesize \textcolor{darkgreen}{\textsc{Institut f"ur Informatik \\[3mm]
  Ludwig-Maximilians-Universit"at Munich \\[1cm] }}}

\end{center}
\end{slide}

\pagestyle{fancy}
\slideframe{none}

\begin{slide}
\begin{center}
{\large \bf Einleitung}
\end{center}
\vspace{3mm}

\end{slide}


\end{document}

