Many ‘open’ projects are developed mainly by people using Unix-based operating systems (Linux, MacOS X, OpenBSD, etc.). This sometimes leads to a rather awkward situation for Windows users. Many of the tools that are assumed to be available (GCC, make, grep, …) simply are not. TeX is luckily cross-platform, and recent versions of TeX Live work hard to work on Windows as well as on *nix systems. However, that can still leave a few issues. The LaTeX3 experimental code has a series of test files, make scripts and so on, to aid development. However, these only work if things like make and bash are actually available. So I’ve recently added a set of batch files to the source store, which hopefully do basically the same thing but using Windows tools. I’ve had to require Perl for the test scripts, as these need to be parsed and re-formatted. The batch files also need a command-line .zip program: I tend to use 7-Zip. Hopefully, though, these are not too much to ask for!
In the longer term, LuaTeX should mean that auxiliary stuff can be done using Lua, as it will be available cross-platform. However, it could be many years before we reach that state!