Pricing In A Deal?

Neil Irwin wonders why the stock market hasn't tanked in anticipation of the fiscal cliff:

The basic question is who is judging the political temperature better: Those at a healthy remove who know that these things usually work themselves out, if at the last possible minute? Or those who are closest to the action, who see little visible evidence that a deal is reachable by the end of the year? Here’s the thing: They both could be right. It may be that the thing that will finally force the parties to negotiate in earnest will be increasingly desperate calls from supporters in the business community, or a few hairy days on the financial markets, of 5 or 7 or 9 percent declines.