It appears that the http.us.debian.org site ftp1.us.debian.org, aka IP 206.187.92.15, isn't correctly mirroring the unstable/main directories for powerpc. Specifically: http://http.us.debian.org/debian/distsunstable/main/binary-powerpc is an empty directory.
I took the liberty of emailing the webmaster of that site regarding the mirror failure. This is the source of those annoying 404 Not Found errors that crop up when using the Debian package tools. -- John
