Electronics are printed on silicon, with Plastic Logic technology, they are printed on plastic.

Plastic is more durable and flexible, cheaper (in the long run) and can be produced in non-clean rooms.

"polymer transistors and electronics"

http://en.wikipedia.org/wiki/Plastic_Logic

If so, how does this make the iPad a competitor?

They were making an iPad like product and have announced it way before the iPad was announced. But now that looks sort of sunk. As a consumer product it doesn't look like they'll be able to pull it off. But their technology seems fantastic and can make them a successful company lower on the supply chain.

What is 'Plastic Electronics?'

Essentially this is silicon chips without the silicon. Electronic circuits printed onto cheaper plastic substrates which offer promise of cheaper electronics with interesting properties such as flexibility. http://en.wikipedia.org/wiki/Organic_electronics