All those effects still have a place in a "flat" design. They're just more subtle and you actually have to go look for them instead of being distracted by them. Their main purpose is to create affordance for UI elements.

For example, the new Google has a very subtle gradient from light to dark; so while you say it's "flat" there is actually simulated light being cast from a third dimension. This helps it stand out on (appear on top of) a uniform background.