Since the fix of nodejs/node-v0.x-archive#1746 it became possible to use compiled .node binaries on Windows as file modules.
As @Benvie has said at node-ffi/node-ffi#30, providing some compiled binaries is the usual mode of things for Windows.
However, as @kkaefer has said at TryGhost/node-sqlite3#48, there's no clear blessed path to distribute such binaries via npm.
Some of the existing Node.js modules are, in fact, binary, but they are built by npm for end users (not by their developers for packaging), and, as far as I know, currently none of those are intended to run on Windows.
Foreseeing a future in which not every JavaScript developer on Windows is ready to have somewhat huge Visual C++ 2010 Express installed for building Node.js modules (even though that installation is free of charge), I suggest that npm should introduce some package.json options and thus facilitate providing of two versions of pre-compiled binaries (that is, win32 version and win64 version) — pre-compiled by their own module developers.