As I thought, Dinesh confirmed that the partial methods (Insert, Update, Delete) on a DataContext are overriding instead of notifications. The reason for this is so that you can override the default logic, so you could redirect the update via a stored procedure.
However, you can continue processing the default way, even within the partial method by calling this.ExecuteDynamicXXXXX() method.
For example, the method below overrides the default UpdateOrder logic, writes out information to the console then continues to execute the update by calling ExecuteDynamicUpdate();
partial class DataClasses1DataContext
partial void UpdateOrder(Order instance)
This is definitely something to be aware of, but the new methods means that it is not a problem if you want to include custom logic but still process the command in the same way.