William Boxer at 2012-05-25 16:10:37:
I approach High-Concept as an idea that when summed up in 1-2 sentences contains the protagonist, the nemesis, and the stakes. So, for instance, Armageddon to me is high concept because you can sum it up as, "Oil drillers must land on an asteroid and blow it up before it crashes into the Earth."
I wouldn't consider Sideways high-concept because within your summary there are no stakes involved.