The "bdist_rpm" doesn't work with RPM 2.x. This means that building RPMs will only work on Red Hat 6.x -- and presumably any version of Mandrake (since Mandrake started as a fork of Red Hat 6.0), and recent SuSE versions as well, but I don't know how recent.
Does anyone care? I don't anymore, since I finally got around to upgrading to Red Hat 6. If compatibility with RPM 2.x matters to you, then please dig in to the bdist_rpm command, figure out why it doesn't work, and submit a patch. Otherwise Distutils will only be able to build RPMs with RPM 3.