Microsoft has released a beta of Windows Cache Extension for PHP

Windows Cache Extension for PHP is a PHP accelerator that is used to increase the speed of PHP applications running on Windows and Windows Server. Once the Windows Cache Extension for PHP is enabled and loaded by the PHP engine, PHP applications can take advantage of the functionality without any code modifications.

Features
PHP 5.2 and PHP 5.3 support
Configurable file cache
Configurable PHP opcode cache
Relative file path cache
PHP functions to obtain information about the cache status

Windows Cache Extension for PHP Beta