Broken http.us.debian.org site
It appears that the http.us.debian.org site ftp1.us.debian.org, aka IP
188.8.131.52, isn't correctly mirroring the unstable/main directories
for powerpc. Specifically:
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.