I personally doubt that Google monitors/records voice conversations. IANAL, but some states have "all party consent" rules (sometimes called eavesdropping or wiretapping laws) where all parties to a conversation must agree to information being recorded. Even if the GV user agrees to terms that allow monitoring, the person on the other end might not agree to those terms.

Many doctors don't give out confidential information over the phone at all.

It is kind of funny seeing all this concern over IT privacy while other forms of privacy aren't taken nearly as seriously but are probably more important (as one of the previous posters mentioned-documents face up in passenger seats of parked cars, "attorney eyes only" documents being read by attorneys on airplanes, etc...)

Also, just FYI it's HIPAA, not HIPPA