As is mentioned in this new article from Visual Studio Magazine today, a new caching accelerator for PHP has been released for the Windows platform.
The new "Windows Cache Extension for PHP" solution, currently in beta release, is an accelerator that works with the PHP engine in Windows and Windows Server. Microsoft released two versions. Users of PHP 5.2 can download the beta here, while PHP 5.3 users can get it here.
The extension works with the Web Platform Installer and IIS versions 7.5, 7.0, 6.5 and 5.1. Ruslan Yakushev has blogged a bit more information about the extension noting that it only works with non-thread-safe builds of PHP and IIS needs to be able to use FastCGI modules.
For more details on using the extension, check out this guide from Microsoft.