There is an IRC channel to discuss PHP internals Development for Windows on Freenode in channel #php-dev-win

Windows Build, step by step

Windows Release Management

Windows Installer

Windows Custom Built Dependencies (libs you need for compiling)

Massive Todo List

How do I get my PECL extension compiling on windows?

Links

Slides about developing PHP Internals on Windows

Get ready to compile php on windows in 10 mins