Is there a way to list all the build targets available in a build file?

Using MSBuild 2.0/3.5 : Custom Task

You could write a custom msbuild task like this :

using System;
using System.Collections.Generic;
using Microsoft.Build.BuildEngine;
using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;

namespace MSBuildTasks
{
  public class GetAllTargets : Task
  {
    [Required]
    public String ProjectFile { get; set; }

    [Output]
    public ITaskItem[] Targets { get; set; }

    public override bool Execute()
    {
      var project = new Project(BuildEngine as Engine);
      project.Load(ProjectFile);

      var taskItems = new List<ITaskItem>(project.Targets.Count);
      foreach (Target target in project.Targets)
      {
        var metadata = new Dictionary<string, string>
                        {
                          {"Condition", target.Condition},
                          {"Inputs", target.Inputs},
                          {"Outputs", target.Outputs},
                          {"DependsOnTargets", target.DependsOnTargets}
                        };
        taskItems.Add(new TaskItem(target.Name, metadata));
      }

      Targets = taskItems.ToArray();

      return true;
    }
  }
}

That you’ll use like that:

<Target Name="TestGetAllTargets">
  <GetAllTargets ProjectFile="$(MSBuildProjectFile)">
    <Output ItemName="TargetItems" TaskParameter="Targets"/>
  </GetAllTargets>

  <Message Text="Name: %(TargetItems.Identity) Input: %(TargetItems.Input) --> Output: %(TargetItems.Output)"/>
</Target>

Using MSBuild 4.0 : Inline task

With MSBuild 4 you could use the new shiny thing : the inline task. Inline task allows you to define the behavior directly in msbuild file.

<UsingTask TaskName="GetAllTargets"
           TaskFactory="CodeTaskFactory"
           AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v4.0.dll" >
  <ParameterGroup>
    <ProjectFile ParameterType="System.String" Required="true"/>
    <TargetsOut ParameterType="Microsoft.Build.Framework.ITaskItem[]" Output="true"/>
  </ParameterGroup>
  <Task>
    <Reference Include="System.Xml"/>
    <Reference Include="Microsoft.Build"/>
    <Reference Include="Microsoft.Build.Framework"/>
    <Using Namespace="Microsoft.Build.Evaluation"/>
    <Using Namespace="Microsoft.Build.Execution"/>
    <Using Namespace="Microsoft.Build.Utilities"/>
    <Using Namespace="Microsoft.Build.Framework"/>
    <Code Type="Fragment" Language="cs">
      <![CDATA[
        var project = new Project(ProjectFile);
        
        var taskItems = new List<ITaskItem>(project.Targets.Count);
        foreach (KeyValuePair<string, ProjectTargetInstance> kvp in project.Targets)
        {
          var target = kvp.Value;
          var metadata = new Dictionary<string, string>
                          {
                            {"Condition", target.Condition},
                            {"Inputs", target.Inputs},
                            {"Outputs", target.Outputs},
                            {"DependsOnTargets", target.DependsOnTargets}
                          };
          taskItems.Add(new TaskItem(kvp.Key, metadata));
        }

        TargetsOut = taskItems.ToArray();
      ]]>
    </Code>
  </Task>
</UsingTask>

<Target Name="Test">
  <GetAllTargets ProjectFile="$(MSBuildProjectFile)">
    <Output ItemName="TargetItems" TaskParameter="TargetsOut"/>  
  </GetAllTargets>

  <Message Text="%(TargetItems.Identity)"/>
</Target>