Index: wp-admin/includes/plugin-install.php
===================================================================
--- wp-admin/includes/plugin-install.php	(revision 21117)
+++ wp-admin/includes/plugin-install.php	(working copy)
@@ -128,7 +128,7 @@
 			<option value="tag"<?php selected('tag', $type) ?>><?php _ex('Tag', 'Plugin Installer'); ?></option>
 		</select>
 		<?php endif; ?>
-		<input type="search" name="s" value="<?php echo esc_attr($term) ?>" />
+		<input type="search" name="s" value="<?php echo esc_attr($term) ?>" autofocus="autofocus" />
 		<label class="screen-reader-text" for="plugin-search-input"><?php _e('Search Plugins'); ?></label>
 		<?php submit_button( __( 'Search Plugins' ), 'button', 'plugin-search-input', false ); ?>
 	</form><?php
Index: wp-admin/includes/theme-install.php
===================================================================
--- wp-admin/includes/theme-install.php	(revision 21117)
+++ wp-admin/includes/theme-install.php	(working copy)
@@ -64,7 +64,7 @@
 	<option value="tag" <?php selected('tag', $type) ?>><?php _ex('Tag', 'Theme Installer'); ?></option>
 	</select>
 	<?php endif; ?>
-	<input type="search" name="s" size="30" value="<?php echo esc_attr($term) ?>" />
+	<input type="search" name="s" size="30" value="<?php echo esc_attr($term) ?>" autofocus="autofocus" />
 	<?php submit_button( __( 'Search' ), 'button', 'search', false ); ?>
 </form>
 <?php