I'm not a PHP developer, but I recognize that it is a very popular scripting language and there are a lot of resources available.  I just came across Phalanger, which is a PHP compiler for .NET.  This is not just CLR support for the PHP language, but a compiler that can take existing PHP script and compile it to run on the .NET Framework (MSIL). 

Under Sample Apps, you'll find popular PHP applications such as PhpMyAdmin, phpBB, and PHP-Nuke 7.5 that were compiled with little or no tweaking.  The Phalanger Forum is running under a compiled version of phpBB.

For PHP developers, this means taking advantage of the .NET Framework class libraries and the speed of truly compiled applications.  Benchmarks provided suggest that PHP applications compiled for .NET realize significant speed improvements and have a much higher throughput.  PHP developers can also take advantage of other .NET components written in C#, VB.NET, or any other CLR language.  For .NET developers, this opens up a whole world of PHP modules and applications that can be tapped for .NET applications.

Currently, Phalanger only works with .NET 1.x and does not run on Mono.  However, these features are on their roadmap.