If you have been using Team Build in beta 2 and have been brave enough to customise it :-), you would have come across CustomActions.targets file. This file was automatically created when you created a build type and got checked in. If you needed to customise your build steps – this is where you would need to plug in your custom task. Now – if you have further been brave enough to try out beta3 Team build – you would find this file missing.
No – its not a bug just that we have gotten rid of it simply because we did not see why we should not recomend the user to simply add his custom steps in the tfsbuild.proj file itself (earlier called TeamBuild.proj) instead of mantaining the overhead of yet another file. So in case you want to plug in your custom tasks in beta 3 – you can do this straight in the tfsbuild.proj file.
Just in case you are already used to customactions.targets or simply want to give it neat and simply by having a separate file for all your custom tasks – you can still create your own customfoo.targets file and import it in the tfsbuild.proj file and you will be good to go!