\documentclass[10pt]{beamer}
%\usetheme{Boadilla}
\setbeamertemplate{blocks}[rounded]
\begin{document}
\begin{frame}
Text 1
\begin{block}{Block Title}
  Block.
\end{block}
Text 2
\end{frame}
\begin{frame}
Text 3
\begin{itemize}
\item Itemized text.
\end{itemize}
Text 4
\end{frame}
\end{document}

% $Id: beamer-block.tex 30014 2009-06-21 23:02:07Z vinc17/prunille $
