On the Developer Tutorials site, there's an article talking about the integration that can be made with PHP6 and .NET Visual Studio:

PHP, .net and Silverlight will be integrated out of the box, along with Visual Studio 2008. The project has long been in the works, but our sources have informed us of an impending announcement that PHP 6 will ship with .net.

The glue between them is a part of the phlanger project.

Elizabeth Smith has set out on something she calls the Great Compile Project - her effort to get all dependencies for PHP and PECL compiled on (at the least) Visual Studio 2005 transparently and provided openly.

Anyone crazy enough to help out is more than welcome. I'm currently working on the GTK dependency stack, which will hit quite a few PHP dependencies and PECL extension dependencies in the process. And yes I'd love to submit my hacks/fixes upstream, if someone could find me some information (where do you send libiconv patches?)

Her post mentions some of the things she's already been working on to help further the cause - compiling various Open Source libraries, figuring out issues surrounding MiniGW and some examples of more complex dependency issues she's come across.

Elizabeth Smith has posted about a new toy she received from the folks at Microsoft that adds in a missing piece of development functionality on Windows - code coverage and testing.

So this evening I managed to get PHPT running my tests (they're just basic .phpt tests but run-tests is..well flakey is a nice description some days) for my winapi php extension wrapped inside a "generic test" for Visual Studio. [...] So what did all this accomplish? I now can run my phpt tests through visual studio and collect code coverage on what they’re testing. Like GCOV, only for windows.

She's also included a screenshot of what the interface and results of the testing look like in the latest Visual Studio tool.