While physics and mathematics have been using the ArXiv preprint/e-print repository for decades, we in the earth sciences haven't had something similar. The benefits of a widely-used preprint repository are large: it should increase the speed at which science is disseminated, reduce the stranglehold of journals on paper access, and potentially provide visibility to controversial or otherwise avant-garde science that the mainstream reviewer/editor pool isn't ready for. The drawbacks are mainly that the work isn't always peer-reviewed, so it's possible that mortally flawed research will get out to readers that aren't willing or able to thoroughly vet the work.
Despite the potential for leakage of bad science, I think that the benefits outweight the costs (which are largely hypothetical) and that most readers of the earth science literature are quite capable of evaluating what science is worth using and building upon and what's not. Unlike economics, for example, geology doesn't have a huge and politically- or idealogically-motivated non-professional readership that may non-critically run with a paper's conclusions. Economists, it's worth noting, still traffic heavily in white papers and preprints despite (or because of?) these possibilities, anyways. This probably speaks to the increases in efficiency afforded by using preprints.
A group of earth scientists has created the EarthArXiv, an earth science preprint service; it seems to be part of a larger umbrella organization called the Center for Open Science that supports open projects and collaboration through services such as this, as well as the Open Science Framework which is a collection of webapps to facilitate the organization's goals.
I uploaded a preprint today, for the first time. It's a paper that I blogged a few days ago, that didn't quite fit in with Geology but will probably go out to Geophysical Research Letters or Tectonics this spring, after I get some higher priority papers off my desk. I like the paper, though it could use a little polish, and I am happy to have a venue other than this blog to share it.
Big thanks to the EarthArXiv team for making this happen!