This is a simpler mechanism. It simply involves the addition of a Windows Batch command task build step before the MSBuild step and the use of a simple find and replace program (FART).
The Batch Step
fart --svn -r AssemblyInfo.cs "[assembly: AssemblyVersion(\"1.0.0.0\")]" "[assembly: AssemblyVersion(\"1.0.%BUILD_NUMBER%.%SVN_REVISION%\")]"
if %ERRORLEVEL%==0 exit /b 1
fart --svn -r AssemblyInfo.cs "[assembly: AssemblyFileVersion(\"1.0.0.0\")]" "[assembly: AssemblyFileVersion(\"1.0.%BUILD_NUMBER%.%SVN_REVISION%\")]"
if %ERRORLEVEL%==0 exit /b 1
exit /b 0
If you are using source control other than svn change the --svn option for the appropriate one for your scm environment.