A quick hack to allow anonymising of all names.

You can make everyone have the name "Bruce" if you want.   }-)

config-dist.php

@@ -234,6 +234,11 @@ $CFG->admin = 'admin';
 //   Print to footer (works with the default theme)
 //   define('MDL_PERFTOFOOT', true);
 //
+// Force displayed usernames
+//   A little hack to anonymise user names for all students.  If you set these 
+//   then all non-teachers will always see these for every person.
+//       $CFG->forcefirstname = 'Bruce';
+//       $CFG->forcelastname  = 'Simpson';
 
 //=========================================================================
 // ALL DONE!  To continue installation, visit your main page with a browser

lib/moodlelib.php

@@ -1984,6 +1984,15 @@ function fullname($user, $override=false) {
         return '';
     }
 
+    if (!$override) {
+        if (!empty($CFG->forcefirstname)) {
+            $user->firstname = $CFG->forcefirstname;
+        }
+        if (!empty($CFG->forcelastname)) {
+            $user->lastname = $CFG->forcelastname;
+        }
+    }
+
     if (!empty($SESSION->fullnamedisplay)) {
         $CFG->fullnamedisplay = $SESSION->fullnamedisplay;
     }