apt-get update no longer functional after apt-get dist-upgrade earlier this morning

[Piszcz, Justin]

# apt-get update Get:1 http://mirrors.rcn.net testing Release.gpg [189B] Hit http://mirrors.rcn.net testing Release                                   Get:2 http://secure-testing.debian.net etch/security-updates Release.gpg [189B] Hit http://mirrors.rcn.net testing/main Packages                             Hit http://mirrors.rcn.net testing/non-free Packages Get:3 http://ftp.nerim.net etch Release.gpg [189B] Hit http://mirrors.rcn.net testing/contrib Packages                          Hit http://mirrors.rcn.net testing/main Sources Hit http://mirrors.rcn.net testing/non-free Sources Hit http://secure-testing.debian.net etch/security-updates Release Hit http://mirrors.rcn.net testing/contrib Sources                  Ign http://secure-testing.debian.net etch/security-updates Release  Hit http://ftp.nerim.net etch Release         Ign http://ftp.nerim.net etch Release        Hit http://secure-testing.debian.net etch/security-updates/main Packages Hit http://secure-testing.debian.net etch/security-updates/contrib Packages Hit http://ftp.nerim.net etch/main Packages Hit http://secure-testing.debian.net etch/security-updates/non-free Packages Hit http://secure-testing.debian.net etch/security-updates/main Sources Hit http://secure-testing.debian.net etch/security-updates/contrib Sources Hit http://secure-testing.debian.net etch/security-updates/non-free Sources Fetched 379B in 1s (296B/s) Reading package lists... Done W: GPG error: http://secure-testing.debian.net etch/security-updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 946AA6E18722E71E W: GPG error: http://ftp.nerim.net etch Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 07DC563D1F41B907 W: You may want to run apt-get update to correct these problems #   Any idea how to fix?