An MSBuild script to download all packages referenced from a set of .NET solution's packages.config files.

RestoreAllPackages.msbuild.xml

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

  <PropertyGroup>
    <SolutionDir>.</SolutionDir>
  </PropertyGroup>
  
  <!-- This targets file sets a handful of nuget-related properties. -->
  <Import Project=".nuget/NuGet.targets"/>

  <!-- This builds an ItemGroup with all the packages.config file in the solution folder. -->  
  <ItemGroup>
     <PackageConfigFiles Include="$(SolutionDir.Trim('\\'))\**\packages.config"/>
  </ItemGroup>
  
  <!-- The Inputs and Outputs attributes tell MSBuild to batch this target across each 
       item in the input itemgroup. -->
  <Target Name="InstallAllPackages" Inputs="@(PackageConfigFiles)"
                                    Outputs="%(Identity).ignore">
    <PropertyGroup>
        <PackagesConfig>%(PackageConfigFiles.Identity)</PackagesConfig>
        <!-- The following RestoreCommand node is copied from the included NuGet.targets file.
             It must be included in a propertygroup here so that it gets properly populated 
             with each packages.config file as MSBuild batches this target across 
             @(PackageConfigFiles). 
         -->
        <RestoreCommand>$(NuGetCommand) install "$(PackagesConfig)" -source "$(PackageSources)"  $(NonInteractiveSwitch) $(RequireConsentSwitch) -solutionDir $(PaddedSolutionDir)</RestoreCommand>
    </PropertyGroup>
    <Message Text="Found: $(PackagesConfig)"/>
    <Message Text="Installing..."/>
    <Message Text=""/>
    <Exec Command="$(RestoreCommand)"/>
  </Target>
  
</Project>