Very basic Mapnik XML stylesheet showing ways and nodes

I'm trying to create an extremely basic Mapnik XML stylesheet, so that I can display purely all ways and nodes in an OSM extract, for debugging purposes. It doesn't need to look pretty.

I am running this against a flat-file .osm file, using the Geofabrik extract suggested at: http://wiki.openstreetmap.org/wiki/Mapnik/Rendering_OSM_XML_data_directly

I can't get the nodes to show - what am I doing wrong? The ways are showing fine.

<?xml version="1.0" encoding="utf-8"?>
<Map background-color="#f2efe9" srs="+proj=latlong +datum=WGS84">

       <Style name="highways">
                <Rule>
                        <Filter>[highway] <>''</Filter>
                        <LineSymbolizer stroke="#808080" stroke-width="2" stroke-linejoin="round" stroke-linecap="round" />
                </Rule>
        </Style>

        <Style name="nodes">
               <Rule>
                        <Filter>[mapnik:geometry_type]=point</Filter>
                        <PointSymbolizer file="./hospital.16.svg" />
                </Rule>
        </Style>
</Map>