It's not just hybrid drivers who can improve their mileage by changing their driving habits. Some days I do it in my VW Passat. Many cars have an in-dash computer that provides plenty of information. It's not a new technology. I had a crappy used 1989 Audi that had one.
Though the Passat is basically a 29 mpg car, I've been able to nurse nearly 40 mpg out of some round trips. It helps not to be running late. Surface roads are better than superhighways if they don't have many stoplights. The brakes are death to mileage; brakes turn gas-created momentum into waste heat. (Even the Prius's regenerative braking can't recapture 100% of the energy that would otherwise become heat. Demon entropy!) Upshifting earlier than normal helps, too; this car was built to travel at 40 mph in fifth. In fact, many of the same driving techniques that help in snow also help with mileage - keep it smooth, don't do anything hasty, slow down. A good rule even when driving for performance is to reach your top speed and upshift. The only cost is the downshift you'll need to accelerate.
But miles per gallon is not the end goal here. The idea is to use fewer gallons. If you get 20% better mileage on a route that's 30% longer, you've optimized the wrong number. I have one trip I make where I have a choice between the arterial highway route at 80 mph and 30 mpg and the surface road route at 35 mph and 35 mpg. Most important, though, the surface route is only a little more than half the distance. It takes about 5 extra minutes on the outward leg but taking the return trip this way led me to discover that it's actually faster.
Then again, there's a coworker who not only drives a Prius using a hill-avoiding route, she also carpools. For my part, I have a short commute, and I work from home a lot, but I burn my virtue up in trips to pick my daughter up from school.
Click image for public domain release posted on Wikimedia Commons by Rudolph Stricker.