There is also a 10% improvement in energy recovery through braking and battery output is 30% higher than the previous generation. Biggest novelty probably is that during light crusing the engine shuts down and the car can be powered by the electric motor alone. This is not quite like the Prius, which can use electricity only from a complete stop and travel relatively long distances at moderate speed on battery alone, but it's a step forward.
Update - August 31st, 2005: Those who are looking for pictures of the new 2006 Honda Civic can go here: Photos of the sedan, photos of the civic 2006 coupe, photos of the Si Coupe, photos of the 2006 civic hybrid, summary of the three versions, civic 2006 powertrain details.
Update - September 6, 2005: Here is a new post about the Honda Civic 2006 with lots of links, specs and photos.
Update - September 9, 2005: Those who can't afford an hybrid car like the Honda Civic hybrid (or the Toyota Prius) should have a look at our post about small Japanese cars that are coming to North-America. Nothing new to the rest of the world, but finally some quality fuel efficient cars in the land of the SUV.
Update - October 3rd, 2005: Along with the small Japanese cars mentioned above, the Mercedes B-Cass car is now available in Canada (and soon in the US, probably). It is a car to consider for luxury car buyers that are looking to buy something small and that gets relatively good gas mileage (compared to most other luxury vehicles), though it is not quite as green as it could be.
Update - November 9th, 2005: For comparison's sake, here's what's new in the Toyota Prius for 2006.