Well, I guess it depends upon to what kind of assessment results you are referring. If it is class grades (such as a chapter test score or a project grade) then a note home is appropriate. Also, many schools now have online parental access to student grades, so parents can see how their students are doing in "live time." Of course, there is huge responsibility on the teacher to make sure all of his/her grading is up to date. Nothing is worse than, as a parent, logging into the computer system and seeing that one of your kid's teachers ...
This response describes a few different methods by which assessment findings are disseminated to the various stakeholders in a school setting.