This is to have a namespace that is for user pages, where each user has AUTH_EDIT on their own page, without the need to add an entry for every user to the ACL.

This patch has been applied after the Separate Admin Login patch:

--- auth.php.bak	2009-02-24 15:29:16.000000000 +0000
+++ auth.php	2009-02-24 15:42:49.000000000 +0000
@@ -430,6 +430,13 @@
   $max = AUTH_ADMIN;
   if($_SESSION[DOKU_COOKIE]['auth']['admin'] == true) { $max =  AUTH_READ; }
 
+  //if users home page, minimum is AUTH_EDIT (but max above beats min here)
+  $min = AUTH_NONE;
+  $fullname = $_SESSION[DOKU_COOKIE]['auth']['info']['name'];
+  $fullname = str_replace(' ', '_', $fullname);
+  $fullname = strtolower($fullname);
+  if($id == 'users:'.$fullname) { $min = AUTH_EDIT; }
+
   //make sure groups is an array
   if(!is_array($groups)) $groups = array();
 
@@ -471,7 +478,7 @@
     }
     if($perm > -1){
       //we had a match - return it
-      return min($perm,$max);
+      return min(max($perm,$min),$max);
     }
   }
 
@@ -494,7 +501,7 @@
         }
       }
       //we had a match - return it
-      return min($perm,$max);
+      return min(max($perm,$min),$max);
     }
 
     //get next higher namespace

This is a hand-hacked version that doesn't require the other tip to be applied (you may have to fix it up):

--- auth.php.bak	2009-02-24 15:29:16.000000000 +0000
+++ auth.php	2009-02-24 15:42:49.000000000 +0000
@@ -430,6 +430,13 @@
   // if no ACL is used always return upload rights
   if(!$conf['useacl']) return AUTH_UPLOAD;
 
+  //if users home page, minimum is AUTH_EDIT (but max above beats min here)
+  $min = AUTH_NONE;
+  $fullname = $_SESSION[DOKU_COOKIE]['auth']['info']['name'];
+  $fullname = str_replace(' ', '_', $fullname);
+  $fullname = strtolower($fullname);
+  if($id == 'users:'.$fullname) { $min = AUTH_EDIT; }
+
   //make sure groups is an array
   if(!is_array($groups)) $groups = array();
 
@@ -471,7 +478,7 @@
     }
     if($perm > -1){
       //we had a match - return it
-      return $perm;
+      return max($perm,$min);
     }
   }
 
@@ -494,7 +501,7 @@
         }
       }
       //we had a match - return it
-      return $perm;
+      return max($perm,$min);
     }
 
     //get next higher namespace

If you want the users to create their own user page you must change the AUTH_EDIT on the line

if($id == 'users:'.$fullname) { $min = AUTH_EDIT; }

to AUTH_CREATE, like:

if($id == 'users:'.$fullname) { $min = AUTH_CREATE; }

This other version use the user login name instead the user name, and also grants create permission for the owner user.

--- auth.php.orig       2009-02-14 04:13:25.000000000 -0800
+++ auth.php    2009-11-13 09:42:21.000000000 -0800
@@ -415,6 +415,13 @@
   // if no ACL is used always return upload rights
   if(!$conf['useacl']) return AUTH_UPLOAD;

+  //if users home page, minimum is AUTH_CREATE (but max above beats min here)
+  if($id == 'users:'.$user) {
+    $min = AUTH_CREATE;
+  } else {
+    $min = AUTH_NONE;
+  }
+
   //make sure groups is an array
   if(!is_array($groups)) $groups = array();

@@ -456,7 +463,7 @@
     }
     if($perm > -1){
       //we had a match - return it
-      return $perm;
+      return max($perm,$min);
     }
   }

@@ -479,7 +486,7 @@
         }
       }
       //we had a match - return it
-      return $perm;
+      return max($perm,$min);
     }

     //get next higher namespace