The new version of WAMP5 is now online.
(WAMP5 installs Apache, PHP5 and MySQL on your Windows)
WAMP5 now includes PHP 5.0.1, the PECL extensions, sqlitemanager 0.9.8...
Many other new features have been added, to know them see the changelog on the Wampserver website.
Of course you can directly upgrade from version 1.0 or 1.1 (except if you have installed the Apache 2 add-on, in that case, save all your data, uninstall and reinstall).