Paul Rabinow has just announced that a number of Foucault lectures are now available online. I’m pretty sure these are newly available in this audio format.
Howison lectures October 1980, parts 1-4
Parrhesia 1983 parts 1-6
Rabinow seminar and recordings, including a phone call to Foucault (in French) May 1983 (link is apparently incorrect for this one. Update: by jiggery pokery, I’ve figured out the phone call file is here.)
Il faut défendre la société, 1976
Sécurité, territoire, population, 1978
Naissance de la biopolitique, 1979
Gouvernement de soi et des autres, 1983 (and 1984, see Update below).
While these are not new texts (apart maybe from the discussion in Rabinow’s office, which sounds like Hubert Dreyfus was there as well) they may still be useful for those who want to hear the actual lectures as delivered. (It certainly makes you appreciate the task of the editors who had to transcribe and edit the lectures!).
Update II: If you look carefully you can also find the recordings of the 1984 lectures which were published earlier this year in French. They are not listed on the site explicitly. Here is the first one.