Index: wp-includes/option.php
===================================================================
--- wp-includes/option.php	(revision 21559)
+++ wp-includes/option.php	(working copy)
@@ -32,8 +32,10 @@
 function get_option( $option, $default = false ) {
 	global $wpdb;
 
+	$filter = is_ms_switched() ? 'blog_option_' : 'option_';
+
 	// Allow plugins to short-circuit options.
-	$pre = apply_filters( 'pre_option_' . $option, false );
+	$pre = apply_filters( 'pre_' . $filter . $option, false );
 	if ( false !== $pre )
 		return $pre;
 
@@ -48,7 +50,7 @@
 		// prevent non-existent options from triggering multiple queries
 		$notoptions = wp_cache_get( 'notoptions', 'options' );
 		if ( isset( $notoptions[$option] ) )
-			return apply_filters( 'default_option_' . $option, $default );
+			return apply_filters( 'default_' . $filter . $option, $default );
 
 		$alloptions = wp_load_alloptions();
 
@@ -67,7 +69,7 @@
 				} else { // option does not exist, so we must cache its non-existence
 					$notoptions[$option] = true;
 					wp_cache_set( 'notoptions', $notoptions, 'options' );
-					return apply_filters( 'default_option_' . $option, $default );
+					return apply_filters( 'default_' . $filter . $option, $default );
 				}
 			}
 		}
@@ -78,7 +80,7 @@
 		if ( is_object( $row ) )
 			$value = $row->option_value;
 		else
-			return apply_filters( 'default_option_' . $option, $default );
+			return apply_filters( 'default_' . $filter . $option, $default );
 	}
 
 	// If home is not set use siteurl.
@@ -88,7 +90,7 @@
 	if ( in_array( $option, array('siteurl', 'home', 'category_base', 'tag_base') ) )
 		$value = untrailingslashit( $value );
 
-	return apply_filters( 'option_' . $option, maybe_unserialize( $value ) );
+	return apply_filters( $filter . $option, maybe_unserialize( $value ) );
 }
 
 /**