This weekend a test rebuild of quantal quetzal did start for the amd64, i386 and armhf architectures. The test rebuild is now finished for the main and restricted components, and continues with the universe and multiverse components.
Results can be seen at http://people.ubuntuwire.org/~wgrant/rebuild-ftbfs-test/test-rebuild-2012092...
The archive for the test rebuild is https://launchpad.net/ubuntu/+archive/test-rebuild-20120922
Please help fixing the build failures for the final release.
Note that an upload won't show up in the superseded sections, if it is uploaded to quantal-proposed, but didn't propagate yet to quantal.
Matthias