Ryan is a shocker, but it makes sense. The Romney campaign is really floundering and they need something that will create buzz and give them momentum moving forward. Tim Pawlenty or Rob Portman wouldn't do that. This is really similar to the Palin choice. It's hard to believe, but that was actually a positive for McCain. I hope people will be smart enough to see that Ryan is an empty suit who consistently lies about basic economics, but I doubt that will happen. It's a good choice for Romney.
Intrade, for those who don't know, is a prediction market that allows people (in other countries, because in America, placing bets online is a tool of the antichrist) to bet on political outcomes. It gives a good picture of the probability that certain events will take place. Currently, the market thinks Ryan is 96% likely to be the choice. Here is a chart that shows what the market believed the odds of Ryan being chosen were over the last year and a half. It shows just how surprising this pick is.