Minecart with Furnace

In Seecret Friday Update 7, Notch implemented powered Minecarts.

See the Minecart article for information on standard minecarts.

Crafting
A powered Minecart is crafted from a Furnace and a Minecart, as shown below:

Destroying a Powered Minecart will give you back a Furnace and regular Minecart, however any fuel used will be lost.

Usage
To use the Powered Minecart, first place it on a track. Select your fuel (currently only coal or charcoal works) and right-click on the Minecart. When right-clicking on the Minecart, you want to face the direction you want it to travel. You can make the cart change direction by right-clicking it while facing the opposite direction of travel. No coal will be lost doing this.

Important Notes

 * Breaking a powered minecart gives a plain cart and the furnace back (but not fuel).
 * Powered minecarts cannot push other carts around 180-degree hairpin turns.
 * A player in a cart adds significant weight, requiring more power to push.
 * 1/1 (and possibly 1/2) slopes are too steep for a single powered cart to push a single occupied cart uphill. 1/3 slopes appear to be gradual enough for success.
 * Going up at a slope of 1/3 (two flat-rails between each up-ramp) will allow you to push your train upwards, as it appears the powered  minecarts have force applied in intervals.
 * Multiple powered minecarts yield more pushing power; 2 powered minecarts can push a player-occupied minecart up a 1/1 slope. (although very slowly).
 * A Single powered minecart can push an occupied minecart up a 1/1 slope if there are additional minecarts being pushed (possibly due to bumping physics).
 * When a powered minecart runs out of fuel, it does not break.
 * One piece of coal seems to power the minecart for 4 minutes. Distance varies based on ramps and other objects on the track.

Trivia

 * Storage and powered minecarts are the first crafted items created from two separate crafted items.