I'm involved, in one way or another, with several projects that build and run on Windows systems. Now most of the developers tend to be Unix people, so the Win32 side of the fence rarely gets as much love as it should. Part of the reason, frankly, is that it's really easy to get a development version of your average piece of open source software up and running on a Unix machine, and it's really hard to do the same thing on Windows.
Why is it so hard on Windows? Well, there are two major reasons.
First, the tools tend to be harder to get. Your average Unix machine either comes with all the compilers and libraries you're likely to need, or you can get them really easily. The same tools don't tend to come in the box with your standard Windows install, so you have to go out and get them. This means spending money, or at least it did until very recently when Microsoft released their Visual Studio 2005 Express Edition, basically just a cut-down version of Visual Studio that you can download for free. Even with the appearance of a free-as-in-beer win32 development environment (I don't consider cygwin or mingw real alternatives, if I want to use Unix tools I'll do it on a Unix system) it's still pretty hard to get things up and running. Installing the Microsoft Platform SDK and getting Visual Studio to recognize it took me most of this morning, for example. That said, this is a Beta version of the IDE, so hopefully it'll be easier when the real thing ships.
The second problem is sort of a catch-22. It's hard to build most projects on Win32 systems because not too many people do it. This means that the ones who do build them tend to be able to deal with the "Pain in the Ass" nature of the system, so the process doesn't tend to get better. In Unix land there are enough people going through the pain that sooner or later they fix the problems. Thus, fewer people work on the win32 versions because the barrier to entry is so high, and the cycle repeats itself.
Anyway, this weekend I got a bit motivated, and actually downloaded and installed Visual C++ 2005 Express Edition, got the Microsoft Platform SDK working (for the record, the instructions they post don't seem to work for me, I had to use the trick mentioned here where you copy the headers and libraries into the Visual Studio install directory), and I'm inching towards getting Subversion and APR to actually build.
I'm hoping that with the advent of some decent free-as-in-beer tools it'll be easier for us Unix people to actually confirm that things work in Windows land, and the first step seems to be going through the process and figuring out how to streamline it a bit.