An e-mail:

It seems to me that the truly machiavellian primary vote is for Hillary!, since she and she alone is the candidate most likely to secure a GOP victory …

Another:

Seriously, as someone who now recognizes that McCain will win the nomination and who wants him to win the general election, I’d rather that he face Hillary than Obama. Wouldn’t it be good if lots of Republicans crossed over to vote for Hillary?

Maybe. But my view is that during primary season, each party should play in its own sandbox. Anything else feels vaguely like a point-shaving scheme.