An example of a XNA Content Pipeline tast

gistfile1.xml

...
  <UsingTask TaskName="BuildContent" AssemblyName="Microsoft.Xna.Framework.Content.Pipeline, Version=4.0.0.0, Culture=neutral, PublicKeyToken=842cf8be1de50553" />

  <PropertyGroup>
    <XnaInstall>C:\Program Files (x86)\Microsoft XNA\XNA Game Studio\v4.0\References\Windows\x86</XnaInstall>
  </PropertyGroup>

  <ItemGroup>
    <PipelineAssembly Include="$(XnaInstall)\Microsoft.Xna.Framework.Content.Pipeline.AudioImporters.dll" />
    <PipelineAssembly Include="$(XnaInstall)\Microsoft.Xna.Framework.Content.Pipeline.EffectImporter.dll" />
    <PipelineAssembly Include="$(XnaInstall)\Microsoft.Xna.Framework.Content.Pipeline.FBXImporter.dll" />
    <PipelineAssembly Include="$(XnaInstall)\Microsoft.Xna.Framework.Content.Pipeline.TextureImporter.dll" />
    <PipelineAssembly Include="$(XnaInstall)\Microsoft.Xna.Framework.Content.Pipeline.XImporter.dll" />
  </ItemGroup>

  <ItemGroup>
    <Content Include="Fonts\DebugFont.spritefont">
      <Name>DebugFont</Name>
      <Importer>FontDescriptionImporter</Importer>
      <Processor>FontDescriptionProcessor</Processor>
    </Content>
    <Content Include="Shaders\FloodFill.fx">
      <Name>FloodFill</Name>
      <Importer>EffectImporter</Importer>
      <Processor>EffectProcessor</Processor>
    </Content>
    <Content Include="Shaders\Multiply.fx">
      <Name>Multiply</Name>
      <Importer>EffectImporter</Importer>
      <Processor>EffectProcessor</Processor>
    </Content>
  </ItemGroup>

  <Target Name="BeforeBuild">
    <BuildContent SourceAssets="@(Content)" PipelineAssemblies="@(PipelineAssembly)" TargetPlatform="Windows" TargetProfile="Reach" OutputDirectory="$(OutDir)"/>
  </Target>
...