See http://fedoraproject.org/wiki/RolandMcGrath/BuildID about this whole scheme, which we want to have in F8. Patch at http://people.redhat.com/roland/build-id/debugedit-build-id.patch adds the feature, please incorporate or tell me how best to get it in upstream.
Added to rpm5.org HEAD. Thanks for the patch.
Also added to rpm.org 4.4.2.1 (rc2) and will be in next rawhide build.