Andrew writes eloquently on McCain (keating 5) and his lack of character during the pig fight here. It's good stuff.
Yes, McCain made a decision that revealed many appalling things about him. In the end, his final concern is not national security. No one who cares about national security would pick as vice-president someone who knows nothing about it as his replacement. No one who cares about this country's safety would gamble the security of the world on a total unknown because she polled well with the Christianist base. No person who truly believed that the surge was integral to this country's national security would pick as his veep candidate a woman who, so far as we can tell anything, opposed it at the time.