Comment 2 for bug 1067832

Solved the problem by issuing this command:

$ sudo -i
# apt-get clean
# cd /var/lib/apt
# mv lists lists.old
# mkdir -p lists/partial
# apt-get clean
# apt-get update

Source: http://askubuntu.com/questions/1877/what-is-the-easiest-way-to-resolve-apt-get-badsig-gpg-errors

This still needs to be integrated in some way so that the user does not need to do their own plumbing.