WordPress/wp-includes/version.php

<?php
/**
 * This holds the version number in a separate file so we can bump it without cluttering the SVN
 */

/**
 * The WordPress version string
 *
 * @global string $wp_version
 */
$wp_version = '3.1-alpha';

/**
 * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
 *
 * @global int $wp_db_version
 */
$wp_db_version = 15477;

/**
 * Holds the TinyMCE version
 *
 * @global string $tinymce_version
 */
$tinymce_version = '3392';

/**
 * Holds the cache manifest version
 *
 * @global string $manifest_version
 */
$manifest_version = '20100530';

/**
 * Holds the required PHP version
 *
 * @global string $required_php_version
 */
$required_php_version = '4.3';

/**
 * Holds the required MySQL version
 *
 * @global string $required_mysql_version
 */
$required_mysql_version = '4.1.2';