WordPress 3.2 will require PHP 5.2.4 and MySQL 5.0. This plugin by ryanduff preforms a simple check and lets you know if you’re ready.
Server requirements from WordPress Codex
WordPress server requirements for Version 3.2 (Spring 2011):
PHP version 5.2.4 or greater
MySQL version 5.0.15 or greater
(Optional (required for multi-site)) Apache mod_rewrite module (for clean URIs known as Permalinks)
WordPress server requirements for Version 2.9, 3.0, 3.1:
PHP version 4.3 or greater
MySQL version 4.1.2 or greater
(Optional (required for multi-site)) Apache mod_rewrite module (for clean URIs known as Permalinks)
WordPress Codex: http://codex.wordpress.org/Hosting_WordPress
Download Plugin: http://wordpress.org/extend/plugins/wordpress-requirements-check/