SLD - place label on each multipoint

I have a multipoint geometry (a single geometry containing multiple points) and I want to place a label on each of the points (the label is always the same). Is it possible to achieve this with SLD? Right now the label is only displayed on a single point.

My SLD looks like this:

<?xml version="1.0" encoding="ISO-8859-1"?>
<StyledLayerDescriptor version="1.0.0"
xsi:schemaLocation="http://www.opengis.net/sld StyledLayerDescriptor.xsd"
xmlns="http://www.opengis.net/sld"
xmlns:ogc="http://www.opengis.net/ogc"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <NamedLayer>
    <Name>Multipoint with labels</Name>
    <UserStyle>
      <Title>Default Point</Title>
      <Abstract>A sample style that draws a point</Abstract>
      <FeatureTypeStyle>
        <Rule>
          <Name>rule1</Name>
          <Title>Red Square</Title>
          <Abstract>A 6 pixel square with a red fill and no stroke</Abstract>
          <PointSymbolizer>
            <Graphic>
              <Mark>
                <WellKnownName>square</WellKnownName>
                <Fill>
                  <CssParameter name="fill">#FF0000</CssParameter>
                </Fill>
              </Mark>
              <Size>6</Size>
            </Graphic>
          </PointSymbolizer>
          <TextSymbolizer>
            <Label>NAME</Label>
          </TextSymbolizer>
        </Rule>
      </FeatureTypeStyle>
    </UserStyle>
  </NamedLayer>
</StyledLayerDescriptor>

By default the GeoServer label engine goes to a lot of trouble to not label multiple times on the same feature, so this is hard!

I finally managed it using the following (ugly) SLD:

   <Rule>
      <Title>Capitals</Title>
              <TextSymbolizer>
         <Geometry>
            <ogc:Function name="getGeometryN">
                <ogc:PropertyName>the_geom</ogc:PropertyName>
                <ogc:Literal>0</ogc:Literal>
            </ogc:Function>
          </Geometry>
        <Label>ID</Label>
      </TextSymbolizer>
      <TextSymbolizer>
         <Geometry>
            <ogc:Function name="getGeometryN">
                <ogc:PropertyName>the_geom</ogc:PropertyName>
                <ogc:Literal>1</ogc:Literal>
            </ogc:Function>
          </Geometry>
        <Label>ID</Label>
      </TextSymbolizer>
       <TextSymbolizer>
         <Geometry>
            <ogc:Function name="getGeometryN">
                <ogc:PropertyName>the_geom</ogc:PropertyName>
                <ogc:Literal>2</ogc:Literal>
            </ogc:Function>
          </Geometry>
        <Label>ID</Label>
      </TextSymbolizer>
              <TextSymbolizer>
         <Geometry>
            <ogc:Function name="getGeometryN">
                <ogc:PropertyName>the_geom</ogc:PropertyName>
                <ogc:Literal>3</ogc:Literal>
            </ogc:Function>
          </Geometry>
        <Label>ID</Label>
      </TextSymbolizer>
    </Rule>

However this assumes you know how many points there are in your largest multi-point, and that is quite small (otherwise it's a lot of copy & paste).

I had originally hoped to be able to use the vertices function or possibly the labelAllGroup vendor option, but sadly neither worked with multi-points.