You can simply use the standard enumerate and tabular environments:
\documentclass{article}
\begin{document}
\begin{enumerate}
\item Item 1 \par
\begin{tabular}{p{0.25\linewidth}p{0.25\linewidth}p{0.25\linewidth}}
subitem & type & date \\
subitem & type & date \\
\end{tabular}
\item Item 2 \par
\begin{tabular}{p{0.25\linewidth}p{0.25\linewidth}p{0.25\linewidth}}
subitem & type & date \\
subitem & type & date \\
\end{tabular}
\item Item 3 \par
\begin{tabular}{p{0.25\linewidth}p{0.25\linewidth}p{0.25\linewidth}}
subitem & type & date \\
subitem & type & date \\
\end{tabular}
\end{enumerate}
\end{document}

Another option, if you want automatic calculation for the column width, would be to use the tabularx package:
\documentclass{article}
\usepackage{tabularx}
\begin{document}
\begin{enumerate}
\item Item 1 \par
\begin{tabularx}{\linewidth}{XXX}
subitem & type & date \\
subitem & type & date \\
\end{tabularx}
\item Item 2 \par
\begin{tabularx}{\linewidth}{XXX}
subitem & type & date \\
subitem & type & date \\
\end{tabularx}
\item Item 3 \par
\begin{tabularx}{\linewidth}{XXX}
subitem & type & date \\
subitem & type & date \\
\end{tabularx}
\end{enumerate}
\end{document}

subitems. – Peter Grill Mar 14 '12 at 18:32