Matrix in a matrix

Something like this ?

\documentclass{article} 
\usepackage{amsmath}    

\begin{document}

\[
\left[ 
\begin{array}{c@{}c@{}c}
 \left[\begin{array}{cc}
         a_{11} & a_{12} \\
         a_{21} & a_{22} \\
  \end{array}\right] & \mathbf{0} & \mathbf{0} \\
  \mathbf{0} & \left[\begin{array}{ccc}
                       b_{11} & b_{12} & b_{13}\\ 
                       b_{21} & b_{22} & b_{23}\\
                       b_{31} & b_{32} & b_{33}\\
                      \end{array}\right] & \mathbf{0}\\
\mathbf{0} & \mathbf{0} & \left[ \begin{array}{cc}
                                   c_{11} & c_{12} \\
                                   c_{21} & c_{22} \\
                                  \end{array}\right] \\
\end{array}\right]
\]    
\end{document} 

After seven years ... with use of bmatrix from the amsmath package:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\[
\begin{bmatrix}
    \begin{bmatrix}
             a_{11} & a_{12}\\
             a_{21} & a_{22}\\
    \end{bmatrix}   &   \mathbf{0}  &   \mathbf{0}            \\
    \mathbf{0}      & \begin{bmatrix}
                       b_{11} & b_{12} & b_{13}\\
                       b_{21} & b_{22} & b_{23}\\
                       b_{31} & b_{32} & b_{33}\\
                      \end{bmatrix} &   \mathbf{0}          \\
    \mathbf{0}      &   \mathbf{0}  & \begin{bmatrix}
                                       c_{11} & c_{12}\\
                                       c_{21} & c_{22}\\
                                      \end{bmatrix}         \\
\end{bmatrix}
\]
\end{document}