Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.925
diff -u -p -r1.925 common.inc
--- includes/common.inc	18 Jun 2009 21:19:01 -0000	1.925
+++ includes/common.inc	29 Jun 2009 06:54:40 -0000
@@ -2417,7 +2417,7 @@ function drupal_get_css($css = NULL) {
   $no_theme_preprocess = '';
   $no_inline_preprocess = '';
 
-  $preprocess_css = (variable_get('preprocess_css', FALSE) && (!defined('MAINTENANCE_MODE') || MAINTENANCE_MODE != 'update'));
+  $preprocess_css = (variable_get('preprocess_css', 1) && (!defined('MAINTENANCE_MODE') || MAINTENANCE_MODE != 'update'));
   $directory = file_directory_path();
   $is_writable = is_dir($directory) && is_writable($directory) && (variable_get('file_downloads', FILE_DOWNLOADS_PUBLIC) == FILE_DOWNLOADS_PUBLIC);
 
Index: modules/system/system.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.admin.inc,v
retrieving revision 1.158
diff -u -p -r1.158 system.admin.inc
--- modules/system/system.admin.inc	19 Jun 2009 20:35:05 -0000	1.158
+++ modules/system/system.admin.inc	29 Jun 2009 06:54:40 -0000
@@ -1349,7 +1349,7 @@ function system_performance_settings() {
   $form['bandwidth_optimizations']['preprocess_css'] = array(
     '#type' => 'radios',
     '#title' => t('Optimize CSS files'),
-    '#default_value' => intval(variable_get('preprocess_css', 0) && $is_writable),
+    '#default_value' => variable_get('preprocess_css', 1),
     '#disabled' => !$is_writable,
     '#options' => array(t('Disabled'), t('Enabled')),
     '#description' => t('This option can interfere with theme development and should only be enabled in a production environment.'),