This is a very rough implementation of the action feed using the django-activity-stream app (you can install it using easy_install, but please remember to run syncdb afterwards)
I sincerely apologize to everyone whose eyes started bleeding from the UI (can you tell I mostly worked in the backend?) - but I considered the functionality to be the important part for now.
For the moment, the action feed displays all actions performed by other users on the review requests created by the current user.