Index: wp-admin/includes/schema.php
===================================================================
--- wp-admin/includes/schema.php	(revision 31554)
+++ wp-admin/includes/schema.php	(working copy)
@@ -461,7 +461,7 @@
 	// 2.7
 	'large_size_w' => 1024,
 	'large_size_h' => 1024,
-	'image_default_link_type' => 'file',
+	'image_default_link_type' => 'none',
 	'image_default_size' => '',
 	'image_default_align' => '',
 	'close_comments_for_old_posts' => 0,
Index: wp-includes/media-template.php
===================================================================
--- wp-includes/media-template.php	(revision 31554)
+++ wp-includes/media-template.php	(working copy)
@@ -648,7 +648,10 @@
 					</option>
 					<option value="file">
 				<# } else { #>
-					<option value="file" selected>
+					<option value="none" selected>
+						<?php esc_attr_e('None'); ?>
+					</option>
+					<option value="file">
 				<# } #>
 					<# if ( data.model.canEmbed ) { #>
 						<?php esc_attr_e('Link to Media File'); ?>
@@ -667,9 +670,6 @@
 					<option value="custom">
 						<?php esc_attr_e('Custom URL'); ?>
 					</option>
-					<option value="none">
-						<?php esc_attr_e('None'); ?>
-					</option>
 				<# } #>
 				</select>
 			</label>
Index: wp-includes/media.php
===================================================================
--- wp-includes/media.php	(revision 31554)
+++ wp-includes/media.php	(working copy)
@@ -2901,7 +2901,7 @@
 	unset( $tabs['type'], $tabs['type_url'], $tabs['gallery'], $tabs['library'] );
 
 	$props = array(
-		'link'  => get_option( 'image_default_link_type' ), // db default is 'file'
+		'link'  => apply_filters( 'image_default_link_type' , 'none' ), // 'none' by default ( possible options : none, file, post, custom )
 		'align' => get_option( 'image_default_align' ), // empty default
 		'size'  => get_option( 'image_default_size' ),  // empty default
 	);