I am a graduate student in IT at the University of Virginia with a background in writing instruction. It is very exciting to see Professor Jonasson's paper, particularly in this format which is a good example of the constructivist approach itself.
The question/problem of assessment interested me because I ran into it in writing instruction and partially solved it by having students assess themselves. At the end of the course, each student had to write a paper reflecting on what she/he had learned in the course. In this way, I not only found out pretty much how much my students had learned, but sometimes a lot more information to assess them by than I had expected. It seems to me, a constructivist approach would make use of such self-assessment as part of the instructional design.
Of course, if we define assessment as something that is totally objective, we're back at square one.