PKG-INFO has included "Requires" since PEP 314, and I think actually there was tool support for it before that. So it might be a gradual process, but we're getting there. In the meantime, if you can, use a modern tool like "pip". If you can't because you're on Windows, it seems like this new "wheel" format is intended to ease construction of "bdist_wininst" or "bdist_msi" distributions from "sdist" distributions, so that should make your life better too.
