I am running the MSBuild task with ContinueOnError=true:

<MSBuild Projects="@(ComponentToDeploy)"
    Targets="$(DeploymentTargets)"
    Properties="$(CommonProperties);%(AdditionalProperties)"
    ContinueOnError="true" 
    Condition="%(Condition)"/>

So my build always succeeds.

Is there a way to find out if any error occurs?

I could not find any Output of the MSBuild task containing this information. The only way I know is to parse the log file for errors but it looks like a workaround for me.

(I am using MSBuild 4.0)

This is an answer to the last feedback of @Ilya.
I'm using feedback/answer because of the length and formatting restrictions of the comments.

Log is scoped to individual targets or to be more specific tasks...

This was indeed the first question arose when I was reading your comment with the suggestion to use Log.HasLoggedErrors: "Was is the scope of the Log?".
Unfortunately I was not be able to finde a proper documentation. MSND does not help much...
Why did you know it is scoped to the task?
I'm not in doubt about your statement at all! I'm just wondering if there is a proper documentation somewhere.. (I haven't been using MSBuild for years ;-)

In any case, what are you building as project?

My test projects are very simple.
MyTest.project

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

    <UsingTask AssemblyFile="$(MSBuildProjectDirectory)\MyCompany.Tools.MSBuild.Tasks.dll" TaskName="MSBuildWithHasLoggedErrors" />

    <ItemGroup>
msbuild msbuild-task msbuild-4.0
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