This morning Tyler links to an RBC article by Martin Uribe and Stephanie Schmitt-Grohe. Let me just say in advance that I know and like Martin and Stephanie and they do awesome work. However, I found the following sentence in their paper quite bewildering:
We find that anticipated shocks are the most important source of uncertainty.
To which I can only reply: ???????? Folks, only a highly trained macroeconomist could hope to parse that humdinger of a sentence.
The paper is indeed a move back toward pure RBC in that there are no nominal ridigities in the model. However, it does simply assume a host of real rigidities, including the dreaded "investment adjustment costs" on the grounds that there is "a large existing literature
showing that these frictions improve the model’s empirical fit."
For those of you who prefer a nominal rigidity approach but like the idea of exploring the distinction between expected and unexpected shocks, there is a related paper by Northwestern grad student Joshua Davis (paper can be downloaded here) that gets different results about what shocks are important than do Uribe & Schmitt.