DynamicWebPages.de points out that the Windows binary builds have been posted for the in-development version of PHP, version 5.3:

The sources for 5.3 are now on the snaps.php.net page as well as the Windows Binaries for testing the new PHP version. Besides the addition of name spaces, Late Static Binding and dynamic-static calls, this version also has mysqlnd a new native PHP driver for MySQL (as replacement to libmysql). This not only performs better than libmysql, but also is more resource-saving and can also be used more simply, since he does not have any external dependence.

You can download the snapshots and binaries from the snaps.php.net website.