Is it possible to set the user picture as the value of an image field from a node? Use case: On my site, I need a workflow that allows user pictures to be approved.  Users submit images using a special content type.  Of these images, they must designate one as their user picture.  I use the Rules module to manage the approval workflow.  

I managed to get everything set up in Rules so that the picture they designate shows up in their profile appropriately.  However, many modules (such as Privatemsg) make use of Drupal's default user picture.  Is there a way to set the Drupal user picture value with the value from the uploaded field?
A quick grep through privatemsg shows that it is using theme('user_picture'...) so you should be able to copy user-picture.tpl.php from "drupalroot"/modules/user to your theme and edit it to your specifics...just flush caches :)