I only discovered the terms "shale" or "unconventional" gas and "hydraulic fracturing" or "fracking" a couple weeks ago.  I think this is partly due to the fact that I live in France, and this method of drilling doesn't exist in France -- In fact, as of June 30, 2011, hydraulic fracturing is officially forbidden in France, as it is considered highly pollutant.  This is contrary to the >20,000 "fracking" wells in the US that produce a large part of the natural gas production which is 20% of the US's energy mix.

To understand what "fracking" is, check out this explanation from the Gasland website: http://www.gaslandthemovie.com/whats-fracking/

Better yet, go see the movie.  It's free and available to watch online.

Quick synopsis: Josh Fox decides to learn more about the fracking industry after receiving a letter from a fracking company, offering to pay him $100,000 to lease his land.  After what he discovers from traveling across the US and interviewing hundreds of people -- including things like  brown/black/yellow water, running faucets catching on fire, people suffering from migraines and brain lesions, animals losing their hair -- he decides to turn down the offer.

The movie is well-made, and you really get the sensation of a "pathogen" swiftly and quietly infiltrating America --- moreover, the movie's got some really good banjo tunes and a fitting eery/beautiful Radiohead song.  It gets a bit repetitive after a while, and I'm a bit frustrated that he doesn't explain enough about how to react to this situation or find an alternative (he briefly mentions at one point, that we should start by making these wells safer and better regulated, or just switch to solar), but all in all, I highly recommend seeing Gasland.

PS. I saw Waste Land earlier this week.  Also, highly recommended.  I guess I'm into documentaries with the word "land" in them, huh.