The way I organized this project was to create a group for my students so that they can all access and comment on each others work. While this scared me originally, I have done this project now three times and have yet to have a student slip innapropriate comments into a classmates presentation because it shows who is making the comment. Here is a picture of what my group setup looks like.
One source from the VoiceThread website that is very helpful for helping to inspire ideas is http://voicethread.com/about/library/. This site has examples from multiple disciplines and age levels which have provided me with many ideas as to how I can adapt this Web 2.0 technology for meaningful inclusion in my classes.
Another source which may be helpful to educators is http://voicethread4education.wikispaces.com/. This site is a wiki created by an educator to show the different ways VoiceThread is being used by teachers, and has many examples which you could use for your students or for coming up with new ways to incorporate this technology.
Lastly, I have included the rubric as a google document which I use to grade the project and to give the students context on my expectations. This rubric has changed slightly each year I have done the project, so any input would be appreciated.