Writing custom workflows and doing other stuff in FIM 2010, you will at some point need one or more of the well-know GUIDS that is part in FIM 2010. Luckily, Brad Turner, did at short and to the point post with these.
I've put these in my FIM library and use them extensively (see below)
public static Guid BuiltInSynchronizationAccount = new Guid("fb89aefa-5ea1-47f1-8890-abe7797d6497");
public static Guid FIMServiceAccount = new Guid("e05d1f1b-3d5e-4014-baa6-94dee7d68c89");
public static Guid Anonymous = new Guid("b0b36673-d43b-4cfa-a7a2-aff14fd90522");