How to run tasks in parallel in MSBuild

As was stated, you cannot parallelise at the task level or even at the target level. MSBuild only will build projects (i.e. MSBuild project files) in parallel. So you have to use the MSBuild task with multiple projects specified and the BuildInParallel attribute should be set to true. Also make sure that when the build is invoked on the command line that the /m switch is sent it.

My Book: Inside the Microsoft Build Engine : Using MSBuild and Team Foundation Build

Try the new parallel task in the MSBuild Extension Pack - http://mikefourie.wordpress.com/2012/02/29/executing-msbuild-targets-in-parallel-part-1

Here is an example of a way to run msbuild targets in parallel. The idea is same ... presenting this msbuild file itself as a project to build. I copied it from my own question: Evaluate item defined in msbuild task via C#

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="4.0" DefaultTargets="Build">
<Target Name="Build" DependsOnTargets="PrepareEnvironmentForBuild;MapDrives">
    <Exec Command="$(MSBuildBinPath)\msbuild /nologo /clp:Verbosity=quiet $(MSBuildThisFileFullPath) /t:TargetWithConfidentialSteps"/>
    <ItemGroup>
        <StepsToRunInParallel Include="$(MSBuildThisFileFullPath)">
            <Properties>TargetToInvoke=ParallelTarget1</Properties>
        </StepsToRunInParallel>
        <StepsToRunInParallel Include="$(MSBuildThisFileFullPath)">
            <Properties>TargetToInvoke=ParallelTarget2</Properties>
        </StepsToRunInParallel>
    </ItemGroup>
    <MSBuild Projects="@(StepsToRunInParallel)" BuildInParallel="true" StopOnFirstFailure="true" Targets="InvokeInParallelWithinThisProject"/>

</Target>
<Target Name="InvokeInParallelWithinThisProject">
    <MSBuild Projects="$(MSBuildThisFileFullPath)" Targets="$(TargetToInvoke)" StopOnFirstFailure="true"/>
</Target>
<Target Name="ParallelTarget1">
    <Message Text="Hello from ParallelTarget1"/>
</Target>
<Target Name="ParallelTarget2">
    <Message Text="Hello from ParallelTarget2"/>
</Target>
<Target Name="PrepareEnvironmentForBuild">
    <Message Text="Hello from PrepareEnvironmentForBuild"/>
</Target>
<Target Name="MapDrives">
    <Message Text="Hello from MapDrives"/>
</Target>
<Target Name="TargetWithConfidentialSteps">
    <Message Text="Hush! Verbosity on the wrapper does not affect the Exec call." Importance="High"/>
</Target>

MSBuild has a /m command line switch to tell it the maximum number of concurrent processes to build with. The default value is 1. /m:x will use x processes. /m will use the number of processors on computer.

I've used this as part of a shortcut in Visual Studio to run builds quicker by compiling projects in parallel. Scott Hanselman has a few posts about it here and here.