The Marcellus shale is real - just like the Barnett, Fayetesville and Haynesville plays were real. They all have a lot of natuiral gas but probably economical at todays prices in a few small sweet spots. Production in the Barnett, Fayettesville and Haynesville has been declining for some time and probably will not pick up until NG is north of $5.
The Marcellus is the newest NG play.. Production is still increasing but production is more or less restricted to 3 counties in the northeast of Pennsylvania and 3 counties near Pittsburgh i.e. sweet spots. The rest is marginal.
The Marcellus is a little different because Pennsylvania/West Virginia did not have much of an intrastructure for NG. The Barnett/Haynesville/Fayetteville did. Consequently the Marcellus has 1000 to 2000 drilled but unconnected wells.. These are slowly being connected and are the reason Marcellus NG production is still increasing. When these 1000 to 2000 wells are connected - within the next 12-18 months - NG productuion in the Marcellus will do exactly what NG production did in the Barnett/Haynesville/Fayettesville - decline. There are not enough new wells being drilled in the Marcellus to keep NG production stable.
There is nothing unique about the Marcellus. The astonishingly high production decline rates are the same, the cost of drilling wells is the same, the royalties are the same etc. And when NG is somewhere above $5 the Marcellus will profitable.