For those who have been waiting for an answer, he was just on AM 1280 in Minnesota and was asked about her. He said it was a "shrewd" pick on McCain's part, and that she seemed like a good person who he hoped would help steer McCain in the right direction on limiting government and making it less invasive in people's lives. But he also said that you shouldn't "hold your breath" because McCain probably isn't going to be influenced like Bush was with Cheney.
He then went on to say he thinks people should vote for someone like Barr or Baldwin, rather then try and vote for the lesser of two evils, though he doesn't seem to have plans to endorse either (still.)