[Atomic-S (OP)]

Is the ethanol being made today coming primarily from the ears of corn, or is the entire corn plant used? Is there any other type of plant which is significantly used in this industry?

[another_someone]

Don't know about over there, but since alcohol is produced by fermenting sugars, I would have thought that plants such as sugar cane (or sugar beet) would do better at it (and I thought that much of Brazil's massive biofuel (ethanol) production is from sugar cane).

[eric l]

The ethanol is produced from the corn kernels, not even from the complete ear.  The stems are used cattle feed mainly, and the "woody" part of the ear is often used as fuel.  (In fact, I know of no other application yet, although fibreboard production may be a possibility). 
The advantage of cereals (corn, wheat, rice or whatever) is that they can be dried at or near the place where they are grown, and as dried product can be stored over many years.  This means that you have the possibility of a constant rate of production of ethanol over the year, while sugar beets or sugar cane are typically "campaign" products.  Of course, you could use the campaign to produce sugar, and use the sugar to produce ethanol during the rest of the year.

[Atomic-S (OP)]

Obviously, were some way to use the whole plant developed, it would be much more efficient use of agricultural resources.

[RD]

The looming food crisis
Land that was once used to grow food is increasingly being turned over to biofuels.
This may help us to fight global warming - but it is driving up food prices throughout the world and making life increasingly hard in developing countries.

http://www.guardian.co.uk/environment/2007/aug/29/food.g2