On the JSLabs blog today, there's a quick tutorial talking about how to transfer PHP scripts (without much altering, depending on the functionality used) over to be compiled into an ASP.net application. The real key is in the Phlanger software.
Phalanger is a new PHP implementation introducing the PHP language into the family of compiled .NET languages. It provides PHP applications an execution environment that is fast and extremely compatible with the vast array of existing PHP code.
Phlanger allows you to compiles PHP to the MSIL (Microsoft Intermediate Language), use any .NET object in a PHP application and integrates well with Visual Studio.