\documentclass[a4paper,11pt]{article}

\usepackage{fullpage}
\pagestyle{empty}

\makeatletter
\def\APtitle#1{\def\@APtitle{#1}}
\def\APauthor#1{\def\@APauthor{#1}}
\def\APaffiliation#1{\def\@APaffiliation{#1}}
\def\APmaketitle{%
\clearpage\begin{center}%
{\bfseries \LARGE \@APtitle}\\\bigskip
{\large \@APauthor}\\\medskip
{\@APaffiliation}\\\medskip
\end{center}}
\makeatother

\begin{document}

%% Sample 1
\APtitle{\LaTeX Template for Poster Submission\\ to APLAS 2009}
\APauthor{Kiminori Matsuzaki}
\APaffiliation{%
Graduate School of Information Science and Technology, \\
University of Tokyo, Japan\\
\texttt{kmatsu@ipl.t.u-tokyo.ac.jp}}

\APmaketitle

This is a \LaTeX template for the poster submission to APLAS 2009.
Each presenter should e-mail a  1-2 page abstract  in PDF or PostScript
(including the title, authors, affiliations, and a summary of the work).

%% End of Sample 1

%% Sample 2
\APtitle{\LaTeX Template for Poster Submission\\ to APLAS 2009: Sample 2}
\APauthor{Kiminori Matsuzaki$^\dag$ and Zhenjiang Hu$^\ddag$}
\APaffiliation{%
$^\dag$Graduate School of Information Science and Technology, \\
University of Tokyo, Japan\\
\texttt{kmatsu@ipl.t.u-tokyo.ac.jp}\\
\medskip
$^\ddag$National Institute of Informatics, Japan\\
\texttt{xxx@yyy.zzz}}

\APmaketitle

This is a sample for two authors with difference affiliations.
%% End of Sample 2

\end{document}