Yes, brisk acceleration and then getting off the gas quickly can yield better gas mileage. It all comes down to getting the ICE (Internal Cumbustion Engine - the gas engine) to run as little as possible. The Prius engine uses a slightly different combustion cycle than typical gasoline engines, and unlike typical gas engines it's about as efficient under heavy load as it is under light load.

So the key is to load the engine heavily by making a brisk accelleration and then getting off the gas to coast as much as possible. This is true of the Toyota hybrid. I don't know if it's true of the Ford and Honda.

The second key to good mileage is to drive in a way that minimizes how much you need to use the brakes. Although the brakes are regenerative, the regeneration process is not very efficient. There are a lot of losses in the braking-generation-battery-motor energy path. The most efficient use of a hybrid's kinetic energy is simply to continue to coast as long as practical. If you use the brakes to convert that kinetic energy to stored electrical energy, and then use that electrical energy to re-accellerate later, you wind up with a lot less motion energy than you started with. Something about Newton's Second Law.

In practice this is a tricky one to achieve because there are other people on the road, and really long, slow coasts to a stop are pretty annoying for other drivers. Until the majority of people are driving hybrids, nobody will understand what we're up to. :) So in heavy traffic I bag it and drive like everyone else. But when nobody else is around, I can frequently be seen sauntering up to stop signs.

Lastly, I've discovered lately that A/C usage makes a big difference in city driving, apparently because it forces the ICE to recharge the battery more often. I don't notice such a big difference on the freeway.