For me it appears that XML::XSLT croaks when it tries to open an external XML file. Line 62 of blog.xsl confirms it:

    <xsl:for-each select="document('menu.xml')/menu/item">
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Have you provided the file menu.xml for the XSLT processor? I guess you have not...:-)

What really makes me wonder here is that XML::LibXSLT gives fairly sane output, even without the menu.xml file. Now this is really strange! Though, I admit that I am not really an expert of XSLT....

Update: after setting the debug_callback for XML::LibXSLT it seems that the parser just silently ignores the missing file here (only noing that the for-each did not produce a node list). XML::XSLT appears to be much more picky here...