Hi Bruno,
We're in the process of refactoring the Registration library and bringing most of it into the main ExcelDna.Integration assembly.
I'm hoping to simplify the default registration behaviour in future.
The code from the AsyncTaskUtil class from ExcelDna.Registration has now been pulled into ExcelDna.Integration.ExcelAsyncUtil.
I suppose we have to think about whether to put some compatibility shims in place, but adapting your code to the new name should be easy.
-Govert