The first one is the discovery of liquids rich gas plays such as the Eagle Ford whose economics are driven by natural gas liquids (derived from processing high BTU natural gas) and oil. The gas that comes off of these plays is essentially a residual cash stream which does not drive the economics of the wells. This results in natural gas being produced that is not dependent on current pricing.
The second is the discovery of the Marcellus Shale. The Marcellus has been a quiet revolution in the oil & gas business as it is located on the east coast (in NY, PA, WV) away from traditional oil and gas centers of the last few decades. However, the Marcellus which was producing very little four years ago is now almost producing half of the unconventional shale dry gas in the United States and is continuing to grow exponentially producing over 15 BCF/D. Breakeven prices have been found to be very low in many parts of the play below $3/MCF due to wells that have initial production rates of over 20,000 MCF/D.
Additionally, Marcellus gas is located next to gas using major cities resulting in shorter distances to market. How big is the Marcellus shale? The USGS has estimated over 84 TCF of natural gas resources in the Marcellus making it the largest gas play in the entire country! Currently, the Marcellus is only produced in its southern and central areas with New York banning fracing and thereby shale production. There is a light at the en d of the tunnel for natural gas pricing though as LNG terminals in the United States come online and coal power plants are converted to a cleaner better fuel. Also, thanks to the guidance of energy greats, such as Boone Pickens, many companies are now considering fueling vehicles with natural gas.