Here's one possible solution for the lower part using both xy and tikz-cd:
\documentclass{article}
\usepackage[all]{xy}
\usepackage{tikz-cd}
\begin{document}
$\xymatrix{
& S \ar[ld]^{\pi_{i}} \ar[rd]_{\pi_{j}} &\\
R_{i} \ar[rr]_{\mu_{ji}} & & R_{j} }$
\begin{tikzcd}[column sep=normal]
& S \arrow{dl}{\pi_{i}}\arrow{dr}[swap]{\pi_{j}} & \\
R_{i} \arrow{rr}[swap]{\mu_{ji}} & & R_{j}
\end{tikzcd}
\end{document}

Here's the complete diagram using tikz-cd:
\documentclass{article}
\usepackage{tikz-cd}
\begin{document}
\begin{tikzcd}[column sep=normal,row sep=large]
& Y\arrow{ddl}[swap]{\psi_{i}}\arrow{ddr}{\psi_{j}}\arrow{d}{h} & \\
& S \arrow{dl}{\pi_{i}}\arrow{dr}[swap]{\pi_{j}} & \\
R_{i} \arrow{rr}[swap]{\mu_{ji}} & & R_{j}
\end{tikzcd}
\end{document}

And now using xy:
\documentclass{article}
\usepackage[all]{xy}
\begin{document}
$\xymatrix{
& Y\ar[ldd]_{\psi_{i}}\ar[rdd]^{\psi_{j}}\ar[d]^{h} & \\
& S \ar[ld]^{\pi_{i}} \ar[rd]_{\pi_{j}} & \\
R_{i} \ar[rr]_{\mu_{ji}} & & R_{j} }$
\end{document}

And now, as requested in a comment, with some arrows curved:
\documentclass{article}
\usepackage{tikz-cd}
\begin{document}
\begin{tikzcd}[column sep=normal,row sep=large]
& Y\arrow[bend right]{ddl}[swap]{\psi_{i}}\arrow[bend left]{ddr}{\psi_{j}}\arrow{d}{h} & \\
& S \arrow{dl}{\pi_{i}}\arrow{dr}[swap]{\pi_{j}} & \\
R_{i} \arrow{rr}[swap]{\mu_{ji}} & & R_{j}
\end{tikzcd}
\end{document}

And with xy:
\documentclass{article}
\usepackage[all]{xy}
\begin{document}
$\xymatrix{
& Y\ar@/_/[ldd]_{\psi_{i}}\ar@/^/[rdd]^{\psi_{j}}\ar[d]^{h} & \\
& S \ar[ld]^{\pi_{i}} \ar[rd]_{\pi_{j}} & \\
R_{i} \ar[rr]_{\mu_{ji}} & & R_{j} }$
\end{document}

`, they'll be marked as code, as can be seen in my edit. You can also highlight the code and click the "code" button (with "{}" on it). – Alan Munn May 25 '12 at 4:58S. Also, in xymatrix the@is for changing the arrow style, e.g. for a dashed arrow one writes\ar@{-->}. More examples here. In our case no style was provided, so the arrow probably didn't draw. – Dylan Moreland May 25 '12 at 5:10