Hi Patrick, although i did not try using sharepoint OM doing so, I did it manually by replacing the template of a form library with another one, which is not yet published by infopath client. When to create a new form based on the updated template, the browser downloads the template instead of openning a new form based on it.
So I wonder if the publish procedure is not as simple as updating the template in sharepoint, it might has something extra, isn't it?