You left out the really important quote from that article:
But yields from a grass that only needs to be planted once would deliver an average of 13.1 megajoules of energy as ethanol for every megajoule of petroleum consumed—in the form of nitrogen fertilizers or diesel for tractors—growing them. "It's a prediction because right now there are no biorefineries built that handle cellulosic material" like that which switchgrass provides, Vogel notes. "We're pretty confident the ethanol yield is pretty close." This means that switchgrass ethanol delivers 540 percent of the energy used to produce it, compared with just roughly 25 percent more energy returned by corn-based ethanol according to the most optimistic studies.

That switchgrass article itself states it's calculations are all theoretical.Yeast can't break cellulose down into alcohol. The cellulose must first be broken down into it's component sugars, which is something mankind has yet to master.
-Blast

p.s. FYI, when the trick of breaking cellulose down into yeast-friendly sugars is discovered you won't have to worry trying to find cellulose-based ethanol over corn-based ethanol. It will ALL be cellulose-based. [/quote]

I defer to your chemistry expertise of which I have none, but there are already a lot of cellulosic ethanol plants up and running, but most don't use switchgrass yet:

Commercial Cellulosic Ethanol Plants in the U.S.[73][74]
(Operational or under construction)

Company..... Location..... Feedstock

Abengoa Bioenergy Hugoton, KS Wheat straw
BlueFire Ethanol Irvine, CA Multiple sources
Colusa Biomass Energy Corporation Sacramento, CA Waste rice straw
Coskata Warrenville, IL Biomass, Agricultural and Municipal wastes
DuPont Danisco Cellulosic Ethanol (DDCE) Vonore, TN Corn cobs, switchgrass
Fulcrum BioEnergy Reno, NV Municipal solid waste
Gulf Coast Energy Mossy Head, FL Wood waste
KL Energy Corp. Upton, WY Wood
Mascoma Lansing, MI Wood
POET LLC Emmetsburg, IA Corn cobs
Range Fuels[75] Treutlen County, GA Wood waste
SunOpta Little Falls, MN Wood chips
SweetWater Energy Rochester, NY Multiple Sources
US Envirofuels Highlands County, FL Sweet sorghum
Xethanol Auburndale, FL Citrus peels